perf: Start the restructuring

mv kernel/perf_event.c -> kernel/events/core.c. From there, all further
sensible splitting can happen. The idea is that due to perf_event.c
becoming pretty sizable and with the advent of the marriage with ftrace,
splitting functionality into its logical parts should help speeding up
the unification and to manage the complexity of the subsystem.

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>

2 files changed, 7460 insertions, 0 deletions

diff --git a/kernel/events/Makefile b/kernel/events/Makefile
new file mode 100644
index 000000000000..26c00e4570e5
--- /dev/null
+++ b/kernel/events/Makefile
@@ -0,0 +1,5 @@
+ifdef CONFIG_FUNCTION_TRACER
+CFLAGS_REMOVE_core.o = -pg
+endif
+
+obj-y += core.o
diff --git a/kernel/events/core.c b/kernel/events/core.c
new file mode 100644
index 000000000000..440bc485bbff
--- /dev/null
+++ b/kernel/events/core.c
@@ -0,0 +1,7455 @@
+/*
+ * Performance events core code:
+ *
+ *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
+ *  Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar
+ *  Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
+ *  Copyright  ©  2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
+ *
+ * For licensing details see kernel-base/COPYING
+ */
+
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/cpu.h>
+#include <linux/smp.h>
+#include <linux/idr.h>
+#include <linux/file.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/hash.h>
+#include <linux/sysfs.h>
+#include <linux/dcache.h>
+#include <linux/percpu.h>
+#include <linux/ptrace.h>
+#include <linux/reboot.h>
+#include <linux/vmstat.h>
+#include <linux/device.h>
+#include <linux/vmalloc.h>
+#include <linux/hardirq.h>
+#include <linux/rculist.h>
+#include <linux/uaccess.h>
+#include <linux/syscalls.h>
+#include <linux/anon_inodes.h>
+#include <linux/kernel_stat.h>
+#include <linux/perf_event.h>
+#include <linux/ftrace_event.h>
+#include <linux/hw_breakpoint.h>
+
+#include <asm/irq_regs.h>
+
+struct remote_function_call {
+        struct task_struct *p;
+        int (*func)(void *info);
+        void *info;
+        int ret;
+};
+
+static void remote_function(void *data)
+{
+        struct remote_function_call *tfc = data;
+        struct task_struct *p = tfc->p;
+
+        if (p) {
+                tfc->ret = -EAGAIN;
+                if (task_cpu(p) != smp_processor_id() || !task_curr(p))
+                        return;
+        }
+
+        tfc->ret = tfc->func(tfc->info);
+}
+
+/**
+ * task_function_call - call a function on the cpu on which a task runs
+ * @p:          the task to evaluate
+ * @func:       the function to be called
+ * @info:       the function call argument
+ *
+ * Calls the function @func when the task is currently running. This might
+ * be on the current CPU, which just calls the function directly
+ *
+ * returns: @func return value, or
+ *          -ESRCH  - when the process isn't running
+ *          -EAGAIN - when the process moved away
+ */
+static int
+task_function_call(struct task_struct *p, int (*func) (void *info), void *info)
+{
+        struct remote_function_call data = {
+                .p = p,
+                .func = func,
+                .info = info,
+                .ret = -ESRCH, /* No such (running) process */
+        };
+
+        if (task_curr(p))
+                smp_call_function_single(task_cpu(p), remote_function, &data, 1);
+
+        return data.ret;
+}
+
+/**
+ * cpu_function_call - call a function on the cpu
+ * @func:       the function to be called
+ * @info:       the function call argument
+ *
+ * Calls the function @func on the remote cpu.
+ *
+ * returns: @func return value or -ENXIO when the cpu is offline
+ */
+static int cpu_function_call(int cpu, int (*func) (void *info), void *info)
+{
+        struct remote_function_call data = {
+                .p = NULL,
+                .func = func,
+                .info = info,
+                .ret = -ENXIO, /* No such CPU */
+        };
+
+        smp_call_function_single(cpu, remote_function, &data, 1);
+
+        return data.ret;
+}
+
+#define PERF_FLAG_ALL (PERF_FLAG_FD_NO_GROUP |\
+                       PERF_FLAG_FD_OUTPUT  |\
+                       PERF_FLAG_PID_CGROUP)
+
+enum event_type_t {
+        EVENT_FLEXIBLE = 0x1,
+        EVENT_PINNED = 0x2,
+        EVENT_ALL = EVENT_FLEXIBLE | EVENT_PINNED,
+};
+
+/*
+ * perf_sched_events : >0 events exist
+ * perf_cgroup_events: >0 per-cpu cgroup events exist on this cpu
+ */
+struct jump_label_key perf_sched_events __read_mostly;
+static DEFINE_PER_CPU(atomic_t, perf_cgroup_events);
+
+static atomic_t nr_mmap_events __read_mostly;
+static atomic_t nr_comm_events __read_mostly;
+static atomic_t nr_task_events __read_mostly;
+
+static LIST_HEAD(pmus);
+static DEFINE_MUTEX(pmus_lock);
+static struct srcu_struct pmus_srcu;
+
+/*
+ * perf event paranoia level:
+ *  -1 - not paranoid at all
+ *   0 - disallow raw tracepoint access for unpriv
+ *   1 - disallow cpu events for unpriv
+ *   2 - disallow kernel profiling for unpriv
+ */
+int sysctl_perf_event_paranoid __read_mostly = 1;
+
+/* Minimum for 512 kiB + 1 user control page */
+int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free' kiB per user */
+
+/*
+ * max perf event sample rate
+ */
+#define DEFAULT_MAX_SAMPLE_RATE 100000
+int sysctl_perf_event_sample_rate __read_mostly = DEFAULT_MAX_SAMPLE_RATE;
+static int max_samples_per_tick __read_mostly =
+        DIV_ROUND_UP(DEFAULT_MAX_SAMPLE_RATE, HZ);
+
+int perf_proc_update_handler(struct ctl_table *table, int write,
+                void __user *buffer, size_t *lenp,
+                loff_t *ppos)
+{
+        int ret = proc_dointvec(table, write, buffer, lenp, ppos);
+
+        if (ret || !write)
+                return ret;
+
+        max_samples_per_tick = DIV_ROUND_UP(sysctl_perf_event_sample_rate, HZ);
+
+        return 0;
+}
+
+static atomic64_t perf_event_id;
+
+static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
+                              enum event_type_t event_type);
+
+static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
+                             enum event_type_t event_type,
+                             struct task_struct *task);
+
+static void update_context_time(struct perf_event_context *ctx);
+static u64 perf_event_time(struct perf_event *event);
+
+void __weak perf_event_print_debug(void)        { }
+
+extern __weak const char *perf_pmu_name(void)
+{
+        return "pmu";
+}
+
+static inline u64 perf_clock(void)
+{
+        return local_clock();
+}
+
+static inline struct perf_cpu_context *
+__get_cpu_context(struct perf_event_context *ctx)
+{
+        return this_cpu_ptr(ctx->pmu->pmu_cpu_context);
+}
+
+#ifdef CONFIG_CGROUP_PERF
+
+/*
+ * Must ensure cgroup is pinned (css_get) before calling
+ * this function. In other words, we cannot call this function
+ * if there is no cgroup event for the current CPU context.
+ */
+static inline struct perf_cgroup *
+perf_cgroup_from_task(struct task_struct *task)
+{
+        return container_of(task_subsys_state(task, perf_subsys_id),
+                        struct perf_cgroup, css);
+}
+
+static inline bool
+perf_cgroup_match(struct perf_event *event)
+{
+        struct perf_event_context *ctx = event->ctx;
+        struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+
+        return !event->cgrp || event->cgrp == cpuctx->cgrp;
+}
+
+static inline void perf_get_cgroup(struct perf_event *event)
+{
+        css_get(&event->cgrp->css);
+}
+
+static inline void perf_put_cgroup(struct perf_event *event)
+{
+        css_put(&event->cgrp->css);
+}
+
+static inline void perf_detach_cgroup(struct perf_event *event)
+{
+        perf_put_cgroup(event);
+        event->cgrp = NULL;
+}
+
+static inline int is_cgroup_event(struct perf_event *event)
+{
+        return event->cgrp != NULL;
+}
+
+static inline u64 perf_cgroup_event_time(struct perf_event *event)
+{
+        struct perf_cgroup_info *t;
+
+        t = per_cpu_ptr(event->cgrp->info, event->cpu);
+        return t->time;
+}
+
+static inline void __update_cgrp_time(struct perf_cgroup *cgrp)
+{
+        struct perf_cgroup_info *info;
+        u64 now;
+
+        now = perf_clock();
+
+        info = this_cpu_ptr(cgrp->info);
+
+        info->time += now - info->timestamp;
+        info->timestamp = now;
+}
+
+static inline void update_cgrp_time_from_cpuctx(struct perf_cpu_context *cpuctx)
+{
+        struct perf_cgroup *cgrp_out = cpuctx->cgrp;
+        if (cgrp_out)
+                __update_cgrp_time(cgrp_out);
+}
+
+static inline void update_cgrp_time_from_event(struct perf_event *event)
+{
+        struct perf_cgroup *cgrp;
+
+        /*
+         * ensure we access cgroup data only when needed and
+         * when we know the cgroup is pinned (css_get)
+         */
+        if (!is_cgroup_event(event))
+                return;
+
+        cgrp = perf_cgroup_from_task(current);
+        /*
+         * Do not update time when cgroup is not active
+         */
+        if (cgrp == event->cgrp)
+                __update_cgrp_time(event->cgrp);
+}
+
+static inline void
+perf_cgroup_set_timestamp(struct task_struct *task,
+                          struct perf_event_context *ctx)
+{
+        struct perf_cgroup *cgrp;
+        struct perf_cgroup_info *info;
+
+        /*
+         * ctx->lock held by caller
+         * ensure we do not access cgroup data
+         * unless we have the cgroup pinned (css_get)
+         */
+        if (!task || !ctx->nr_cgroups)
+                return;
+
+        cgrp = perf_cgroup_from_task(task);
+        info = this_cpu_ptr(cgrp->info);
+        info->timestamp = ctx->timestamp;
+}
+
+#define PERF_CGROUP_SWOUT       0x1 /* cgroup switch out every event */
+#define PERF_CGROUP_SWIN        0x2 /* cgroup switch in events based on task */
+
+/*
+ * reschedule events based on the cgroup constraint of task.
+ *
+ * mode SWOUT : schedule out everything
+ * mode SWIN : schedule in based on cgroup for next
+ */
+void perf_cgroup_switch(struct task_struct *task, int mode)
+{
+        struct perf_cpu_context *cpuctx;
+        struct pmu *pmu;
+        unsigned long flags;
+
+        /*
+         * disable interrupts to avoid geting nr_cgroup
+         * changes via __perf_event_disable(). Also
+         * avoids preemption.
+         */
+        local_irq_save(flags);
+
+        /*
+         * we reschedule only in the presence of cgroup
+         * constrained events.
+         */
+        rcu_read_lock();
+
+        list_for_each_entry_rcu(pmu, &pmus, entry) {
+
+                cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
+
+                perf_pmu_disable(cpuctx->ctx.pmu);
+
+                /*
+                 * perf_cgroup_events says at least one
+                 * context on this CPU has cgroup events.
+                 *
+                 * ctx->nr_cgroups reports the number of cgroup
+                 * events for a context.
+                 */
+                if (cpuctx->ctx.nr_cgroups > 0) {
+
+                        if (mode & PERF_CGROUP_SWOUT) {
+                                cpu_ctx_sched_out(cpuctx, EVENT_ALL);
+                                /*
+                                 * must not be done before ctxswout due
+                                 * to event_filter_match() in event_sched_out()
+                                 */
+                                cpuctx->cgrp = NULL;
+                        }
+
+                        if (mode & PERF_CGROUP_SWIN) {
+                                WARN_ON_ONCE(cpuctx->cgrp);
+                                /* set cgrp before ctxsw in to
+                                 * allow event_filter_match() to not
+                                 * have to pass task around
+                                 */
+                                cpuctx->cgrp = perf_cgroup_from_task(task);
+                                cpu_ctx_sched_in(cpuctx, EVENT_ALL, task);
+                        }
+                }
+
+                perf_pmu_enable(cpuctx->ctx.pmu);
+        }
+
+        rcu_read_unlock();
+
+        local_irq_restore(flags);
+}
+
+static inline void perf_cgroup_sched_out(struct task_struct *task)
+{
+        perf_cgroup_switch(task, PERF_CGROUP_SWOUT);
+}
+
+static inline void perf_cgroup_sched_in(struct task_struct *task)
+{
+        perf_cgroup_switch(task, PERF_CGROUP_SWIN);
+}
+
+static inline int perf_cgroup_connect(int fd, struct perf_event *event,
+                                      struct perf_event_attr *attr,
+                                      struct perf_event *group_leader)
+{
+        struct perf_cgroup *cgrp;
+        struct cgroup_subsys_state *css;
+        struct file *file;
+        int ret = 0, fput_needed;
+
+        file = fget_light(fd, &fput_needed);
+        if (!file)
+                return -EBADF;
+
+        css = cgroup_css_from_dir(file, perf_subsys_id);
+        if (IS_ERR(css)) {
+                ret = PTR_ERR(css);
+                goto out;
+        }
+
+        cgrp = container_of(css, struct perf_cgroup, css);
+        event->cgrp = cgrp;
+
+        /* must be done before we fput() the file */
+        perf_get_cgroup(event);
+
+        /*
+         * all events in a group must monitor
+         * the same cgroup because a task belongs
+         * to only one perf cgroup at a time
+         */
+        if (group_leader && group_leader->cgrp != cgrp) {
+                perf_detach_cgroup(event);
+                ret = -EINVAL;
+        }
+out:
+        fput_light(file, fput_needed);
+        return ret;
+}
+
+static inline void
+perf_cgroup_set_shadow_time(struct perf_event *event, u64 now)
+{
+        struct perf_cgroup_info *t;
+        t = per_cpu_ptr(event->cgrp->info, event->cpu);
+        event->shadow_ctx_time = now - t->timestamp;
+}
+
+static inline void
+perf_cgroup_defer_enabled(struct perf_event *event)
+{
+        /*
+         * when the current task's perf cgroup does not match
+         * the event's, we need to remember to call the
+         * perf_mark_enable() function the first time a task with
+         * a matching perf cgroup is scheduled in.
+         */
+        if (is_cgroup_event(event) && !perf_cgroup_match(event))
+                event->cgrp_defer_enabled = 1;
+}
+
+static inline void
+perf_cgroup_mark_enabled(struct perf_event *event,
+                         struct perf_event_context *ctx)
+{
+        struct perf_event *sub;
+        u64 tstamp = perf_event_time(event);
+
+        if (!event->cgrp_defer_enabled)
+                return;
+
+        event->cgrp_defer_enabled = 0;
+
+        event->tstamp_enabled = tstamp - event->total_time_enabled;
+        list_for_each_entry(sub, &event->sibling_list, group_entry) {
+                if (sub->state >= PERF_EVENT_STATE_INACTIVE) {
+                        sub->tstamp_enabled = tstamp - sub->total_time_enabled;
+                        sub->cgrp_defer_enabled = 0;
+                }
+        }
+}
+#else /* !CONFIG_CGROUP_PERF */
+
+static inline bool
+perf_cgroup_match(struct perf_event *event)
+{
+        return true;
+}
+
+static inline void perf_detach_cgroup(struct perf_event *event)
+{}
+
+static inline int is_cgroup_event(struct perf_event *event)
+{
+        return 0;
+}
+
+static inline u64 perf_cgroup_event_cgrp_time(struct perf_event *event)
+{
+        return 0;
+}
+
+static inline void update_cgrp_time_from_event(struct perf_event *event)
+{
+}
+
+static inline void update_cgrp_time_from_cpuctx(struct perf_cpu_context *cpuctx)
+{
+}
+
+static inline void perf_cgroup_sched_out(struct task_struct *task)
+{
+}
+
+static inline void perf_cgroup_sched_in(struct task_struct *task)
+{
+}
+
+static inline int perf_cgroup_connect(pid_t pid, struct perf_event *event,
+                                      struct perf_event_attr *attr,
+                                      struct perf_event *group_leader)
+{
+        return -EINVAL;
+}
+
+static inline void
+perf_cgroup_set_timestamp(struct task_struct *task,
+                          struct perf_event_context *ctx)
+{
+}
+
+void
+perf_cgroup_switch(struct task_struct *task, struct task_struct *next)
+{
+}
+
+static inline void
+perf_cgroup_set_shadow_time(struct perf_event *event, u64 now)
+{
+}
+
+static inline u64 perf_cgroup_event_time(struct perf_event *event)
+{
+        return 0;
+}
+
+static inline void
+perf_cgroup_defer_enabled(struct perf_event *event)
+{
+}
+
+static inline void
+perf_cgroup_mark_enabled(struct perf_event *event,
+                         struct perf_event_context *ctx)
+{
+}
+#endif
+
+void perf_pmu_disable(struct pmu *pmu)
+{
+        int *count = this_cpu_ptr(pmu->pmu_disable_count);
+        if (!(*count)++)
+                pmu->pmu_disable(pmu);
+}
+
+void perf_pmu_enable(struct pmu *pmu)
+{
+        int *count = this_cpu_ptr(pmu->pmu_disable_count);
+        if (!--(*count))
+                pmu->pmu_enable(pmu);
+}
+
+static DEFINE_PER_CPU(struct list_head, rotation_list);
+
+/*
+ * perf_pmu_rotate_start() and perf_rotate_context() are fully serialized
+ * because they're strictly cpu affine and rotate_start is called with IRQs
+ * disabled, while rotate_context is called from IRQ context.
+ */
+static void perf_pmu_rotate_start(struct pmu *pmu)
+{
+        struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
+        struct list_head *head = &__get_cpu_var(rotation_list);
+
+        WARN_ON(!irqs_disabled());
+
+        if (list_empty(&cpuctx->rotation_list))
+                list_add(&cpuctx->rotation_list, head);
+}
+
+static void get_ctx(struct perf_event_context *ctx)
+{
+        WARN_ON(!atomic_inc_not_zero(&ctx->refcount));
+}
+
+static void free_ctx(struct rcu_head *head)
+{
+        struct perf_event_context *ctx;
+
+        ctx = container_of(head, struct perf_event_context, rcu_head);
+        kfree(ctx);
+}
+
+static void put_ctx(struct perf_event_context *ctx)
+{
+        if (atomic_dec_and_test(&ctx->refcount)) {
+                if (ctx->parent_ctx)
+                        put_ctx(ctx->parent_ctx);
+                if (ctx->task)
+                        put_task_struct(ctx->task);
+                call_rcu(&ctx->rcu_head, free_ctx);
+        }
+}
+
+static void unclone_ctx(struct perf_event_context *ctx)
+{
+        if (ctx->parent_ctx) {
+                put_ctx(ctx->parent_ctx);
+                ctx->parent_ctx = NULL;
+        }
+}
+
+static u32 perf_event_pid(struct perf_event *event, struct task_struct *p)
+{
+        /*
+         * only top level events have the pid namespace they were created in
+         */
+        if (event->parent)
+                event = event->parent;
+
+        return task_tgid_nr_ns(p, event->ns);
+}
+
+static u32 perf_event_tid(struct perf_event *event, struct task_struct *p)
+{
+        /*
+         * only top level events have the pid namespace they were created in
+         */
+        if (event->parent)
+                event = event->parent;
+
+        return task_pid_nr_ns(p, event->ns);
+}
+
+/*
+ * If we inherit events we want to return the parent event id
+ * to userspace.
+ */
+static u64 primary_event_id(struct perf_event *event)
+{
+        u64 id = event->id;
+
+        if (event->parent)
+                id = event->parent->id;
+
+        return id;
+}
+
+/*
+ * Get the perf_event_context for a task and lock it.
+ * This has to cope with with the fact that until it is locked,
+ * the context could get moved to another task.
+ */
+static struct perf_event_context *
+perf_lock_task_context(struct task_struct *task, int ctxn, unsigned long *flags)
+{
+        struct perf_event_context *ctx;
+
+        rcu_read_lock();
+retry:
+        ctx = rcu_dereference(task->perf_event_ctxp[ctxn]);
+        if (ctx) {
+                /*
+                 * If this context is a clone of another, it might
+                 * get swapped for another underneath us by
+                 * perf_event_task_sched_out, though the
+                 * rcu_read_lock() protects us from any context
+                 * getting freed.  Lock the context and check if it
+                 * got swapped before we could get the lock, and retry
+                 * if so.  If we locked the right context, then it
+                 * can't get swapped on us any more.
+                 */
+                raw_spin_lock_irqsave(&ctx->lock, *flags);
+                if (ctx != rcu_dereference(task->perf_event_ctxp[ctxn])) {
+                        raw_spin_unlock_irqrestore(&ctx->lock, *flags);
+                        goto retry;
+                }
+
+                if (!atomic_inc_not_zero(&ctx->refcount)) {
+                        raw_spin_unlock_irqrestore(&ctx->lock, *flags);
+                        ctx = NULL;
+                }
+        }
+        rcu_read_unlock();
+        return ctx;
+}
+
+/*
+ * Get the context for a task and increment its pin_count so it
+ * can't get swapped to another task.  This also increments its
+ * reference count so that the context can't get freed.
+ */
+static struct perf_event_context *
+perf_pin_task_context(struct task_struct *task, int ctxn)
+{
+        struct perf_event_context *ctx;
+        unsigned long flags;
+
+        ctx = perf_lock_task_context(task, ctxn, &flags);
+        if (ctx) {
+                ++ctx->pin_count;
+                raw_spin_unlock_irqrestore(&ctx->lock, flags);
+        }
+        return ctx;
+}
+
+static void perf_unpin_context(struct perf_event_context *ctx)
+{
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&ctx->lock, flags);
+        --ctx->pin_count;
+        raw_spin_unlock_irqrestore(&ctx->lock, flags);
+}
+
+/*
+ * Update the record of the current time in a context.
+ */
+static void update_context_time(struct perf_event_context *ctx)
+{
+        u64 now = perf_clock();
+
+        ctx->time += now - ctx->timestamp;
+        ctx->timestamp = now;
+}
+
+static u64 perf_event_time(struct perf_event *event)
+{
+        struct perf_event_context *ctx = event->ctx;
+
+        if (is_cgroup_event(event))
+                return perf_cgroup_event_time(event);
+
+        return ctx ? ctx->time : 0;
+}
+
+/*
+ * Update the total_time_enabled and total_time_running fields for a event.
+ */
+static void update_event_times(struct perf_event *event)
+{
+        struct perf_event_context *ctx = event->ctx;
+        u64 run_end;
+
+        if (event->state < PERF_EVENT_STATE_INACTIVE ||
+            event->group_leader->state < PERF_EVENT_STATE_INACTIVE)
+                return;
+        /*
+         * in cgroup mode, time_enabled represents
+         * the time the event was enabled AND active
+         * tasks were in the monitored cgroup. This is
+         * independent of the activity of the context as
+         * there may be a mix of cgroup and non-cgroup events.
+         *
+         * That is why we treat cgroup events differently
+         * here.
+         */
+        if (is_cgroup_event(event))
+                run_end = perf_event_time(event);
+        else if (ctx->is_active)
+                run_end = ctx->time;
+        else
+                run_end = event->tstamp_stopped;
+
+        event->total_time_enabled = run_end - event->tstamp_enabled;
+
+        if (event->state == PERF_EVENT_STATE_INACTIVE)
+                run_end = event->tstamp_stopped;
+        else
+                run_end = perf_event_time(event);
+
+        event->total_time_running = run_end - event->tstamp_running;
+
+}
+
+/*
+ * Update total_time_enabled and total_time_running for all events in a group.
+ */
+static void update_group_times(struct perf_event *leader)
+{
+        struct perf_event *event;
+
+        update_event_times(leader);
+        list_for_each_entry(event, &leader->sibling_list, group_entry)
+                update_event_times(event);
+}
+
+static struct list_head *
+ctx_group_list(struct perf_event *event, struct perf_event_context *ctx)
+{
+        if (event->attr.pinned)
+                return &ctx->pinned_groups;
+        else
+                return &ctx->flexible_groups;
+}
+
+/*
+ * Add a event from the lists for its context.
+ * Must be called with ctx->mutex and ctx->lock held.
+ */
+static void
+list_add_event(struct perf_event *event, struct perf_event_context *ctx)
+{
+        WARN_ON_ONCE(event->attach_state & PERF_ATTACH_CONTEXT);
+        event->attach_state |= PERF_ATTACH_CONTEXT;
+
+        /*
+         * If we're a stand alone event or group leader, we go to the context
+         * list, group events are kept attached to the group so that
+         * perf_group_detach can, at all times, locate all siblings.
+         */
+        if (event->group_leader == event) {
+                struct list_head *list;
+
+                if (is_software_event(event))
+                        event->group_flags |= PERF_GROUP_SOFTWARE;
+
+                list = ctx_group_list(event, ctx);
+                list_add_tail(&event->group_entry, list);
+        }
+
+        if (is_cgroup_event(event))
+                ctx->nr_cgroups++;
+
+        list_add_rcu(&event->event_entry, &ctx->event_list);
+        if (!ctx->nr_events)
+                perf_pmu_rotate_start(ctx->pmu);
+        ctx->nr_events++;
+        if (event->attr.inherit_stat)
+                ctx->nr_stat++;
+}
+
+/*
+ * Called at perf_event creation and when events are attached/detached from a
+ * group.
+ */
+static void perf_event__read_size(struct perf_event *event)
+{
+        int entry = sizeof(u64); /* value */
+        int size = 0;
+        int nr = 1;
+
+        if (event->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+                size += sizeof(u64);
+
+        if (event->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+                size += sizeof(u64);
+
+        if (event->attr.read_format & PERF_FORMAT_ID)
+                entry += sizeof(u64);
+
+        if (event->attr.read_format & PERF_FORMAT_GROUP) {
+                nr += event->group_leader->nr_siblings;
+                size += sizeof(u64);
+        }
+
+        size += entry * nr;
+        event->read_size = size;
+}
+
+static void perf_event__header_size(struct perf_event *event)
+{
+        struct perf_sample_data *data;
+        u64 sample_type = event->attr.sample_type;
+        u16 size = 0;
+
+        perf_event__read_size(event);
+
+        if (sample_type & PERF_SAMPLE_IP)
+                size += sizeof(data->ip);
+
+        if (sample_type & PERF_SAMPLE_ADDR)
+                size += sizeof(data->addr);
+
+        if (sample_type & PERF_SAMPLE_PERIOD)
+                size += sizeof(data->period);
+
+        if (sample_type & PERF_SAMPLE_READ)
+                size += event->read_size;
+
+        event->header_size = size;
+}
+
+static void perf_event__id_header_size(struct perf_event *event)
+{
+        struct perf_sample_data *data;
+        u64 sample_type = event->attr.sample_type;
+        u16 size = 0;
+
+        if (sample_type & PERF_SAMPLE_TID)
+                size += sizeof(data->tid_entry);
+
+        if (sample_type & PERF_SAMPLE_TIME)
+                size += sizeof(data->time);
+
+        if (sample_type & PERF_SAMPLE_ID)
+                size += sizeof(data->id);
+
+        if (sample_type & PERF_SAMPLE_STREAM_ID)
+                size += sizeof(data->stream_id);
+
+        if (sample_type & PERF_SAMPLE_CPU)
+                size += sizeof(data->cpu_entry);
+
+        event->id_header_size = size;
+}
+
+static void perf_group_attach(struct perf_event *event)
+{
+        struct perf_event *group_leader = event->group_leader, *pos;
+
+        /*
+         * We can have double attach due to group movement in perf_event_open.
+         */
+        if (event->attach_state & PERF_ATTACH_GROUP)
+                return;
+
+        event->attach_state |= PERF_ATTACH_GROUP;
+
+        if (group_leader == event)
+                return;
+
+        if (group_leader->group_flags & PERF_GROUP_SOFTWARE &&
+                        !is_software_event(event))
+                group_leader->group_flags &= ~PERF_GROUP_SOFTWARE;
+
+        list_add_tail(&event->group_entry, &group_leader->sibling_list);
+        group_leader->nr_siblings++;
+
+        perf_event__header_size(group_leader);
+
+        list_for_each_entry(pos, &group_leader->sibling_list, group_entry)
+                perf_event__header_size(pos);
+}
+
+/*
+ * Remove a event from the lists for its context.
+ * Must be called with ctx->mutex and ctx->lock held.
+ */
+static void
+list_del_event(struct perf_event *event, struct perf_event_context *ctx)
+{
+        struct perf_cpu_context *cpuctx;
+        /*
+         * We can have double detach due to exit/hot-unplug + close.
+         */
+        if (!(event->attach_state & PERF_ATTACH_CONTEXT))
+                return;
+
+        event->attach_state &= ~PERF_ATTACH_CONTEXT;
+
+        if (is_cgroup_event(event)) {
+                ctx->nr_cgroups--;
+                cpuctx = __get_cpu_context(ctx);
+                /*
+                 * if there are no more cgroup events
+                 * then cler cgrp to avoid stale pointer
+                 * in update_cgrp_time_from_cpuctx()
+                 */
+                if (!ctx->nr_cgroups)
+                        cpuctx->cgrp = NULL;
+        }
+
+        ctx->nr_events--;
+        if (event->attr.inherit_stat)
+                ctx->nr_stat--;
+
+        list_del_rcu(&event->event_entry);
+
+        if (event->group_leader == event)
+                list_del_init(&event->group_entry);
+
+        update_group_times(event);
+
+        /*
+         * If event was in error state, then keep it
+         * that way, otherwise bogus counts will be
+         * returned on read(). The only way to get out
+         * of error state is by explicit re-enabling
+         * of the event
+         */
+        if (event->state > PERF_EVENT_STATE_OFF)
+                event->state = PERF_EVENT_STATE_OFF;
+}
+
+static void perf_group_detach(struct perf_event *event)
+{
+        struct perf_event *sibling, *tmp;
+        struct list_head *list = NULL;
+
+        /*
+         * We can have double detach due to exit/hot-unplug + close.
+         */
+        if (!(event->attach_state & PERF_ATTACH_GROUP))
+                return;
+
+        event->attach_state &= ~PERF_ATTACH_GROUP;
+
+        /*
+         * If this is a sibling, remove it from its group.
+         */
+        if (event->group_leader != event) {
+                list_del_init(&event->group_entry);
+                event->group_leader->nr_siblings--;
+                goto out;
+        }
+
+        if (!list_empty(&event->group_entry))
+                list = &event->group_entry;
+
+        /*
+         * If this was a group event with sibling events then
+         * upgrade the siblings to singleton events by adding them
+         * to whatever list we are on.
+         */
+        list_for_each_entry_safe(sibling, tmp, &event->sibling_list, group_entry) {
+                if (list)
+                        list_move_tail(&sibling->group_entry, list);
+                sibling->group_leader = sibling;
+
+                /* Inherit group flags from the previous leader */
+                sibling->group_flags = event->group_flags;
+        }
+
+out:
+        perf_event__header_size(event->group_leader);
+
+        list_for_each_entry(tmp, &event->group_leader->sibling_list, group_entry)
+                perf_event__header_size(tmp);
+}
+
+static inline int
+event_filter_match(struct perf_event *event)
+{
+        return (event->cpu == -1 || event->cpu == smp_processor_id())
+            && perf_cgroup_match(event);
+}
+
+static void
+event_sched_out(struct perf_event *event,
+                  struct perf_cpu_context *cpuctx,
+                  struct perf_event_context *ctx)
+{
+        u64 tstamp = perf_event_time(event);
+        u64 delta;
+        /*
+         * An event which could not be activated because of
+         * filter mismatch still needs to have its timings
+         * maintained, otherwise bogus information is return
+         * via read() for time_enabled, time_running:
+         */
+        if (event->state == PERF_EVENT_STATE_INACTIVE
+            && !event_filter_match(event)) {
+                delta = tstamp - event->tstamp_stopped;
+                event->tstamp_running += delta;
+                event->tstamp_stopped = tstamp;
+        }
+
+        if (event->state != PERF_EVENT_STATE_ACTIVE)
+                return;
+
+        event->state = PERF_EVENT_STATE_INACTIVE;
+        if (event->pending_disable) {
+                event->pending_disable = 0;
+                event->state = PERF_EVENT_STATE_OFF;
+        }
+        event->tstamp_stopped = tstamp;
+        event->pmu->del(event, 0);
+        event->oncpu = -1;
+
+        if (!is_software_event(event))
+                cpuctx->active_oncpu--;
+        ctx->nr_active--;
+        if (event->attr.exclusive || !cpuctx->active_oncpu)
+                cpuctx->exclusive = 0;
+}
+
+static void
+group_sched_out(struct perf_event *group_event,
+                struct perf_cpu_context *cpuctx,
+                struct perf_event_context *ctx)
+{
+        struct perf_event *event;
+        int state = group_event->state;
+
+        event_sched_out(group_event, cpuctx, ctx);
+
+        /*
+         * Schedule out siblings (if any):
+         */
+        list_for_each_entry(event, &group_event->sibling_list, group_entry)
+                event_sched_out(event, cpuctx, ctx);
+
+        if (state == PERF_EVENT_STATE_ACTIVE && group_event->attr.exclusive)
+                cpuctx->exclusive = 0;
+}
+
+/*
+ * Cross CPU call to remove a performance event
+ *
+ * We disable the event on the hardware level first. After that we
+ * remove it from the context list.
+ */
+static int __perf_remove_from_context(void *info)
+{
+        struct perf_event *event = info;
+        struct perf_event_context *ctx = event->ctx;
+        struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+
+        raw_spin_lock(&ctx->lock);
+        event_sched_out(event, cpuctx, ctx);
+        list_del_event(event, ctx);
+        raw_spin_unlock(&ctx->lock);
+
+        return 0;
+}
+
+
+/*
+ * Remove the event from a task's (or a CPU's) list of events.
+ *
+ * CPU events are removed with a smp call. For task events we only
+ * call when the task is on a CPU.
+ *
+ * If event->ctx is a cloned context, callers must make sure that
+ * every task struct that event->ctx->task could possibly point to
+ * remains valid.  This is OK when called from perf_release since
+ * that only calls us on the top-level context, which can't be a clone.
+ * When called from perf_event_exit_task, it's OK because the
+ * context has been detached from its task.
+ */
+static void perf_remove_from_context(struct perf_event *event)
+{
+        struct perf_event_context *ctx = event->ctx;
+        struct task_struct *task = ctx->task;
+
+        lockdep_assert_held(&ctx->mutex);
+
+        if (!task) {
+                /*
+                 * Per cpu events are removed via an smp call and
+                 * the removal is always successful.
+                 */
+                cpu_function_call(event->cpu, __perf_remove_from_context, event);
+                return;
+        }
+
+retry:
+        if (!task_function_call(task, __perf_remove_from_context, event))
+                return;
+
+        raw_spin_lock_irq(&ctx->lock);
+        /*
+         * If we failed to find a running task, but find the context active now
+         * that we've acquired the ctx->lock, retry.
+         */
+        if (ctx->is_active) {
+                raw_spin_unlock_irq(&ctx->lock);
+                goto retry;
+        }
+
+        /*
+         * Since the task isn't running, its safe to remove the event, us
+         * holding the ctx->lock ensures the task won't get scheduled in.
+         */
+        list_del_event(event, ctx);
+        raw_spin_unlock_irq(&ctx->lock);
+}
+
+/*
+ * Cross CPU call to disable a performance event
+ */
+static int __perf_event_disable(void *info)
+{
+        struct perf_event *event = info;
+        struct perf_event_context *ctx = event->ctx;
+        struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+
+        /*
+         * If this is a per-task event, need to check whether this
+         * event's task is the current task on this cpu.
+         *
+         * Can trigger due to concurrent perf_event_context_sched_out()
+         * flipping contexts around.
+         */
+        if (ctx->task && cpuctx->task_ctx != ctx)
+                return -EINVAL;
+
+        raw_spin_lock(&ctx->lock);
+
+        /*
+         * If the event is on, turn it off.
+         * If it is in error state, leave it in error state.
+         */
+        if (event->state >= PERF_EVENT_STATE_INACTIVE) {
+                update_context_time(ctx);
+                update_cgrp_time_from_event(event);
+                update_group_times(event);
+                if (event == event->group_leader)
+                        group_sched_out(event, cpuctx, ctx);
+                else
+                        event_sched_out(event, cpuctx, ctx);
+                event->state = PERF_EVENT_STATE_OFF;
+        }
+
+        raw_spin_unlock(&ctx->lock);
+
+        return 0;
+}
+
+/*
+ * Disable a event.
+ *
+ * If event->ctx is a cloned context, callers must make sure that
+ * every task struct that event->ctx->task could possibly point to
+ * remains valid.  This condition is satisifed when called through
+ * perf_event_for_each_child or perf_event_for_each because they
+ * hold the top-level event's child_mutex, so any descendant that
+ * goes to exit will block in sync_child_event.
+ * When called from perf_pending_event it's OK because event->ctx
+ * is the current context on this CPU and preemption is disabled,
+ * hence we can't get into perf_event_task_sched_out for this context.
+ */
+void perf_event_disable(struct perf_event *event)
+{
+        struct perf_event_context *ctx = event->ctx;
+        struct task_struct *task = ctx->task;
+
+        if (!task) {
+                /*
+                 * Disable the event on the cpu that it's on
+                 */
+                cpu_function_call(event->cpu, __perf_event_disable, event);
+                return;
+        }
+
+retry:
+        if (!task_function_call(task, __perf_event_disable, event))
+                return;
+
+        raw_spin_lock_irq(&ctx->lock);
+        /*
+         * If the event is still active, we need to retry the cross-call.
+         */
+        if (event->state == PERF_EVENT_STATE_ACTIVE) {
+                raw_spin_unlock_irq(&ctx->lock);
+                /*
+                 * Reload the task pointer, it might have been changed by
+                 * a concurrent perf_event_context_sched_out().
+                 */
+                task = ctx->task;
+                goto retry;
+        }
+
+        /*
+         * Since we have the lock this context can't be scheduled
+         * in, so we can change the state safely.
+         */
+        if (event->state == PERF_EVENT_STATE_INACTIVE) {
+                update_group_times(event);
+                event->state = PERF_EVENT_STATE_OFF;
+        }
+        raw_spin_unlock_irq(&ctx->lock);
+}
+
+static void perf_set_shadow_time(struct perf_event *event,
+                                 struct perf_event_context *ctx,
+                                 u64 tstamp)
+{
+        /*
+         * use the correct time source for the time snapshot
+         *
+         * We could get by without this by leveraging the
+         * fact that to get to this function, the caller
+         * has most likely already called update_context_time()
+         * and update_cgrp_time_xx() and thus both timestamp
+         * are identical (or very close). Given that tstamp is,
+         * already adjusted for cgroup, we could say that:
+         *    tstamp - ctx->timestamp
+         * is equivalent to
+         *    tstamp - cgrp->timestamp.
+         *
+         * Then, in perf_output_read(), the calculation would
+         * work with no changes because:
+         * - event is guaranteed scheduled in
+         * - no scheduled out in between
+         * - thus the timestamp would be the same
+         *
+         * But this is a bit hairy.
+         *
+         * So instead, we have an explicit cgroup call to remain
+         * within the time time source all along. We believe it
+         * is cleaner and simpler to understand.
+         */
+        if (is_cgroup_event(event))
+                perf_cgroup_set_shadow_time(event, tstamp);
+        else
+                event->shadow_ctx_time = tstamp - ctx->timestamp;
+}
+
+#define MAX_INTERRUPTS (~0ULL)
+
+static void perf_log_throttle(struct perf_event *event, int enable);
+
+static int
+event_sched_in(struct perf_event *event,
+                 struct perf_cpu_context *cpuctx,
+                 struct perf_event_context *ctx)
+{
+        u64 tstamp = perf_event_time(event);
+
+        if (event->state <= PERF_EVENT_STATE_OFF)
+                return 0;
+
+        event->state = PERF_EVENT_STATE_ACTIVE;
+        event->oncpu = smp_processor_id();
+
+        /*
+         * Unthrottle events, since we scheduled we might have missed several
+         * ticks already, also for a heavily scheduling task there is little
+         * guarantee it'll get a tick in a timely manner.
+         */
+        if (unlikely(event->hw.interrupts == MAX_INTERRUPTS)) {
+                perf_log_throttle(event, 1);
+                event->hw.interrupts = 0;
+        }
+
+        /*
+         * The new state must be visible before we turn it on in the hardware:
+         */
+        smp_wmb();
+
+        if (event->pmu->add(event, PERF_EF_START)) {
+                event->state = PERF_EVENT_STATE_INACTIVE;
+                event->oncpu = -1;
+                return -EAGAIN;
+        }
+
+        event->tstamp_running += tstamp - event->tstamp_stopped;
+
+        perf_set_shadow_time(event, ctx, tstamp);
+
+        if (!is_software_event(event))
+                cpuctx->active_oncpu++;
+        ctx->nr_active++;
+
+        if (event->attr.exclusive)
+                cpuctx->exclusive = 1;
+
+        return 0;
+}
+
+static int
+group_sched_in(struct perf_event *group_event,
+               struct perf_cpu_context *cpuctx,
+               struct perf_event_context *ctx)
+{
+        struct perf_event *event, *partial_group = NULL;
+        struct pmu *pmu = group_event->pmu;
+        u64 now = ctx->time;
+        bool simulate = false;
+
+        if (group_event->state == PERF_EVENT_STATE_OFF)
+                return 0;
+
+        pmu->start_txn(pmu);
+
+        if (event_sched_in(group_event, cpuctx, ctx)) {
+                pmu->cancel_txn(pmu);
+                return -EAGAIN;
+        }
+
+        /*
+         * Schedule in siblings as one group (if any):
+         */
+        list_for_each_entry(event, &group_event->sibling_list, group_entry) {
+                if (event_sched_in(event, cpuctx, ctx)) {
+                        partial_group = event;
+                        goto group_error;
+                }
+        }
+
+        if (!pmu->commit_txn(pmu))
+                return 0;
+
+group_error:
+        /*
+         * Groups can be scheduled in as one unit only, so undo any
+         * partial group before returning:
+         * The events up to the failed event are scheduled out normally,
+         * tstamp_stopped will be updated.
+         *
+         * The failed events and the remaining siblings need to have
+         * their timings updated as if they had gone thru event_sched_in()
+         * and event_sched_out(). This is required to get consistent timings
+         * across the group. This also takes care of the case where the group
+         * could never be scheduled by ensuring tstamp_stopped is set to mark
+         * the time the event was actually stopped, such that time delta
+         * calculation in update_event_times() is correct.
+         */
+        list_for_each_entry(event, &group_event->sibling_list, group_entry) {
+                if (event == partial_group)
+                        simulate = true;
+
+                if (simulate) {
+                        event->tstamp_running += now - event->tstamp_stopped;
+                        event->tstamp_stopped = now;
+                } else {
+                        event_sched_out(event, cpuctx, ctx);
+                }
+        }
+        event_sched_out(group_event, cpuctx, ctx);
+
+        pmu->cancel_txn(pmu);
+
+        return -EAGAIN;
+}
+
+/*
+ * Work out whether we can put this event group on the CPU now.
+ */
+static int group_can_go_on(struct perf_event *event,
+                           struct perf_cpu_context *cpuctx,
+                           int can_add_hw)
+{
+        /*
+         * Groups consisting entirely of software events can always go on.
+         */
+        if (event->group_flags & PERF_GROUP_SOFTWARE)
+                return 1;
+        /*
+         * If an exclusive group is already on, no other hardware
+         * events can go on.
+         */
+        if (cpuctx->exclusive)
+                return 0;
+        /*
+         * If this group is exclusive and there are already
+         * events on the CPU, it can't go on.
+         */
+        if (event->attr.exclusive && cpuctx->active_oncpu)
+                return 0;
+        /*
+         * Otherwise, try to add it if all previous groups were able
+         * to go on.
+         */
+        return can_add_hw;
+}
+
+static void add_event_to_ctx(struct perf_event *event,
+                               struct perf_event_context *ctx)
+{
+        u64 tstamp = perf_event_time(event);
+
+        list_add_event(event, ctx);
+        perf_group_attach(event);
+        event->tstamp_enabled = tstamp;
+        event->tstamp_running = tstamp;
+        event->tstamp_stopped = tstamp;
+}
+
+static void perf_event_context_sched_in(struct perf_event_context *ctx,
+                                        struct task_struct *tsk);
+
+/*
+ * Cross CPU call to install and enable a performance event
+ *
+ * Must be called with ctx->mutex held
+ */
+static int  __perf_install_in_context(void *info)
+{
+        struct perf_event *event = info;
+        struct perf_event_context *ctx = event->ctx;
+        struct perf_event *leader = event->group_leader;
+        struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+        int err;
+
+        /*
+         * In case we're installing a new context to an already running task,
+         * could also happen before perf_event_task_sched_in() on architectures
+         * which do context switches with IRQs enabled.
+         */
+        if (ctx->task && !cpuctx->task_ctx)
+                perf_event_context_sched_in(ctx, ctx->task);
+
+        raw_spin_lock(&ctx->lock);
+        ctx->is_active = 1;
+        update_context_time(ctx);
+        /*
+         * update cgrp time only if current cgrp
+         * matches event->cgrp. Must be done before
+         * calling add_event_to_ctx()
+         */
+        update_cgrp_time_from_event(event);
+
+        add_event_to_ctx(event, ctx);
+
+        if (!event_filter_match(event))
+                goto unlock;
+
+        /*
+         * Don't put the event on if it is disabled or if
+         * it is in a group and the group isn't on.
+         */
+        if (event->state != PERF_EVENT_STATE_INACTIVE ||
+            (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE))
+                goto unlock;
+
+        /*
+         * An exclusive event can't go on if there are already active
+         * hardware events, and no hardware event can go on if there
+         * is already an exclusive event on.
+         */
+        if (!group_can_go_on(event, cpuctx, 1))
+                err = -EEXIST;
+        else
+                err = event_sched_in(event, cpuctx, ctx);
+
+        if (err) {
+                /*
+                 * This event couldn't go on.  If it is in a group
+                 * then we have to pull the whole group off.
+                 * If the event group is pinned then put it in error state.
+                 */
+                if (leader != event)
+                        group_sched_out(leader, cpuctx, ctx);
+                if (leader->attr.pinned) {
+                        update_group_times(leader);
+                        leader->state = PERF_EVENT_STATE_ERROR;
+                }
+        }
+
+unlock:
+        raw_spin_unlock(&ctx->lock);
+
+        return 0;
+}
+
+/*
+ * Attach a performance event to a context
+ *
+ * First we add the event to the list with the hardware enable bit
+ * in event->hw_config cleared.
+ *
+ * If the event is attached to a task which is on a CPU we use a smp
+ * call to enable it in the task context. The task might have been
+ * scheduled away, but we check this in the smp call again.
+ */
+static void
+perf_install_in_context(struct perf_event_context *ctx,
+                        struct perf_event *event,
+                        int cpu)
+{
+        struct task_struct *task = ctx->task;
+
+        lockdep_assert_held(&ctx->mutex);
+
+        event->ctx = ctx;
+
+        if (!task) {
+                /*
+                 * Per cpu events are installed via an smp call and
+                 * the install is always successful.
+                 */
+                cpu_function_call(cpu, __perf_install_in_context, event);
+                return;
+        }
+
+retry:
+        if (!task_function_call(task, __perf_install_in_context, event))
+                return;
+
+        raw_spin_lock_irq(&ctx->lock);
+        /*
+         * If we failed to find a running task, but find the context active now
+         * that we've acquired the ctx->lock, retry.
+         */
+        if (ctx->is_active) {
+                raw_spin_unlock_irq(&ctx->lock);
+                goto retry;
+        }
+
+        /*
+         * Since the task isn't running, its safe to add the event, us holding
+         * the ctx->lock ensures the task won't get scheduled in.
+         */
+        add_event_to_ctx(event, ctx);
+        raw_spin_unlock_irq(&ctx->lock);
+}
+
+/*
+ * Put a event into inactive state and update time fields.
+ * Enabling the leader of a group effectively enables all
+ * the group members that aren't explicitly disabled, so we
+ * have to update their ->tstamp_enabled also.
+ * Note: this works for group members as well as group leaders
+ * since the non-leader members' sibling_lists will be empty.
+ */
+static void __perf_event_mark_enabled(struct perf_event *event,
+                                        struct perf_event_context *ctx)
+{
+        struct perf_event *sub;
+        u64 tstamp = perf_event_time(event);
+
+        event->state = PERF_EVENT_STATE_INACTIVE;
+        event->tstamp_enabled = tstamp - event->total_time_enabled;
+        list_for_each_entry(sub, &event->sibling_list, group_entry) {
+                if (sub->state >= PERF_EVENT_STATE_INACTIVE)
+                        sub->tstamp_enabled = tstamp - sub->total_time_enabled;
+        }
+}
+
+/*
+ * Cross CPU call to enable a performance event
+ */
+static int __perf_event_enable(void *info)
+{
+        struct perf_event *event = info;
+        struct perf_event_context *ctx = event->ctx;
+        struct perf_event *leader = event->group_leader;
+        struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+        int err;
+
+        if (WARN_ON_ONCE(!ctx->is_active))
+                return -EINVAL;
+
+        raw_spin_lock(&ctx->lock);
+        update_context_time(ctx);
+
+        if (event->state >= PERF_EVENT_STATE_INACTIVE)
+                goto unlock;
+
+        /*
+         * set current task's cgroup time reference point
+         */
+        perf_cgroup_set_timestamp(current, ctx);
+
+        __perf_event_mark_enabled(event, ctx);
+
+        if (!event_filter_match(event)) {
+                if (is_cgroup_event(event))
+                        perf_cgroup_defer_enabled(event);
+                goto unlock;
+        }
+
+        /*
+         * If the event is in a group and isn't the group leader,
+         * then don't put it on unless the group is on.
+         */
+        if (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE)
+                goto unlock;
+
+        if (!group_can_go_on(event, cpuctx, 1)) {
+                err = -EEXIST;
+        } else {
+                if (event == leader)
+                        err = group_sched_in(event, cpuctx, ctx);
+                else
+                        err = event_sched_in(event, cpuctx, ctx);
+        }
+
+        if (err) {
+                /*
+                 * If this event can't go on and it's part of a
+                 * group, then the whole group has to come off.
+                 */
+                if (leader != event)
+                        group_sched_out(leader, cpuctx, ctx);
+                if (leader->attr.pinned) {
+                        update_group_times(leader);
+                        leader->state = PERF_EVENT_STATE_ERROR;
+                }
+        }
+
+unlock:
+        raw_spin_unlock(&ctx->lock);
+
+        return 0;
+}
+
+/*
+ * Enable a event.
+ *
+ * If event->ctx is a cloned context, callers must make sure that
+ * every task struct that event->ctx->task could possibly point to
+ * remains valid.  This condition is satisfied when called through
+ * perf_event_for_each_child or perf_event_for_each as described
+ * for perf_event_disable.
+ */
+void perf_event_enable(struct perf_event *event)
+{
+        struct perf_event_context *ctx = event->ctx;
+        struct task_struct *task = ctx->task;
+
+        if (!task) {
+                /*
+                 * Enable the event on the cpu that it's on
+                 */
+                cpu_function_call(event->cpu, __perf_event_enable, event);
+                return;
+        }
+
+        raw_spin_lock_irq(&ctx->lock);
+        if (event->state >= PERF_EVENT_STATE_INACTIVE)
+                goto out;
+
+        /*
+         * If the event is in error state, clear that first.
+         * That way, if we see the event in error state below, we
+         * know that it has gone back into error state, as distinct
+         * from the task having been scheduled away before the
+         * cross-call arrived.
+         */
+        if (event->state == PERF_EVENT_STATE_ERROR)
+                event->state = PERF_EVENT_STATE_OFF;
+
+retry:
+        if (!ctx->is_active) {
+                __perf_event_mark_enabled(event, ctx);
+                goto out;
+        }
+
+        raw_spin_unlock_irq(&ctx->lock);
+
+        if (!task_function_call(task, __perf_event_enable, event))
+                return;
+
+        raw_spin_lock_irq(&ctx->lock);
+
+        /*
+         * If the context is active and the event is still off,
+         * we need to retry the cross-call.
+         */
+        if (ctx->is_active && event->state == PERF_EVENT_STATE_OFF) {
+                /*
+                 * task could have been flipped by a concurrent
+                 * perf_event_context_sched_out()
+                 */
+                task = ctx->task;
+                goto retry;
+        }
+
+out:
+        raw_spin_unlock_irq(&ctx->lock);
+}
+
+static int perf_event_refresh(struct perf_event *event, int refresh)
+{
+        /*
+         * not supported on inherited events
+         */
+        if (event->attr.inherit || !is_sampling_event(event))
+                return -EINVAL;
+
+        atomic_add(refresh, &event->event_limit);
+        perf_event_enable(event);
+
+        return 0;
+}
+
+static void ctx_sched_out(struct perf_event_context *ctx,
+                          struct perf_cpu_context *cpuctx,
+                          enum event_type_t event_type)
+{
+        struct perf_event *event;
+
+        raw_spin_lock(&ctx->lock);
+        perf_pmu_disable(ctx->pmu);
+        ctx->is_active = 0;
+        if (likely(!ctx->nr_events))
+                goto out;
+        update_context_time(ctx);
+        update_cgrp_time_from_cpuctx(cpuctx);
+
+        if (!ctx->nr_active)
+                goto out;
+
+        if (event_type & EVENT_PINNED) {
+                list_for_each_entry(event, &ctx->pinned_groups, group_entry)
+                        group_sched_out(event, cpuctx, ctx);
+        }
+
+        if (event_type & EVENT_FLEXIBLE) {
+                list_for_each_entry(event, &ctx->flexible_groups, group_entry)
+                        group_sched_out(event, cpuctx, ctx);
+        }
+out:
+        perf_pmu_enable(ctx->pmu);
+        raw_spin_unlock(&ctx->lock);
+}
+
+/*
+ * Test whether two contexts are equivalent, i.e. whether they
+ * have both been cloned from the same version of the same context
+ * and they both have the same number of enabled events.
+ * If the number of enabled events is the same, then the set
+ * of enabled events should be the same, because these are both
+ * inherited contexts, therefore we can't access individual events
+ * in them directly with an fd; we can only enable/disable all
+ * events via prctl, or enable/disable all events in a family
+ * via ioctl, which will have the same effect on both contexts.
+ */
+static int context_equiv(struct perf_event_context *ctx1,
+                         struct perf_event_context *ctx2)
+{
+        return ctx1->parent_ctx && ctx1->parent_ctx == ctx2->parent_ctx
+                && ctx1->parent_gen == ctx2->parent_gen
+                && !ctx1->pin_count && !ctx2->pin_count;
+}
+
+static void __perf_event_sync_stat(struct perf_event *event,
+                                     struct perf_event *next_event)
+{
+        u64 value;
+
+        if (!event->attr.inherit_stat)
+                return;
+
+        /*
+         * Update the event value, we cannot use perf_event_read()
+         * because we're in the middle of a context switch and have IRQs
+         * disabled, which upsets smp_call_function_single(), however
+         * we know the event must be on the current CPU, therefore we
+         * don't need to use it.
+         */
+        switch (event->state) {
+        case PERF_EVENT_STATE_ACTIVE:
+                event->pmu->read(event);
+                /* fall-through */
+
+        case PERF_EVENT_STATE_INACTIVE:
+                update_event_times(event);
+                break;
+
+        default:
+                break;
+        }
+
+        /*
+         * In order to keep per-task stats reliable we need to flip the event
+         * values when we flip the contexts.
+         */
+        value = local64_read(&next_event->count);
+        value = local64_xchg(&event->count, value);
+        local64_set(&next_event->count, value);
+
+        swap(event->total_time_enabled, next_event->total_time_enabled);
+        swap(event->total_time_running, next_event->total_time_running);
+
+        /*
+         * Since we swizzled the values, update the user visible data too.
+         */
+        perf_event_update_userpage(event);
+        perf_event_update_userpage(next_event);
+}
+
+#define list_next_entry(pos, member) \
+        list_entry(pos->member.next, typeof(*pos), member)
+
+static void perf_event_sync_stat(struct perf_event_context *ctx,
+                                   struct perf_event_context *next_ctx)
+{
+        struct perf_event *event, *next_event;
+
+        if (!ctx->nr_stat)
+                return;
+
+        update_context_time(ctx);
+
+        event = list_first_entry(&ctx->event_list,
+                                   struct perf_event, event_entry);
+
+        next_event = list_first_entry(&next_ctx->event_list,
+                                        struct perf_event, event_entry);
+
+        while (&event->event_entry != &ctx->event_list &&
+               &next_event->event_entry != &next_ctx->event_list) {
+
+                __perf_event_sync_stat(event, next_event);
+
+                event = list_next_entry(event, event_entry);
+                next_event = list_next_entry(next_event, event_entry);
+        }
+}
+
+static void perf_event_context_sched_out(struct task_struct *task, int ctxn,
+                                         struct task_struct *next)
+{
+        struct perf_event_context *ctx = task->perf_event_ctxp[ctxn];
+        struct perf_event_context *next_ctx;
+        struct perf_event_context *parent;
+        struct perf_cpu_context *cpuctx;
+        int do_switch = 1;
+
+        if (likely(!ctx))
+                return;
+
+        cpuctx = __get_cpu_context(ctx);
+        if (!cpuctx->task_ctx)
+                return;
+
+        rcu_read_lock();
+        parent = rcu_dereference(ctx->parent_ctx);
+        next_ctx = next->perf_event_ctxp[ctxn];
+        if (parent && next_ctx &&
+            rcu_dereference(next_ctx->parent_ctx) == parent) {
+                /*
+                 * Looks like the two contexts are clones, so we might be
+                 * able to optimize the context switch.  We lock both
+                 * contexts and check that they are clones under the
+                 * lock (including re-checking that neither has been
+                 * uncloned in the meantime).  It doesn't matter which
+                 * order we take the locks because no other cpu could
+                 * be trying to lock both of these tasks.
+                 */
+                raw_spin_lock(&ctx->lock);
+                raw_spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING);
+                if (context_equiv(ctx, next_ctx)) {
+                        /*
+                         * XXX do we need a memory barrier of sorts
+                         * wrt to rcu_dereference() of perf_event_ctxp
+                         */
+                        task->perf_event_ctxp[ctxn] = next_ctx;
+                        next->perf_event_ctxp[ctxn] = ctx;
+                        ctx->task = next;
+                        next_ctx->task = task;
+                        do_switch = 0;
+
+                        perf_event_sync_stat(ctx, next_ctx);
+                }
+                raw_spin_unlock(&next_ctx->lock);
+                raw_spin_unlock(&ctx->lock);
+        }
+        rcu_read_unlock();
+
+        if (do_switch) {
+                ctx_sched_out(ctx, cpuctx, EVENT_ALL);
+                cpuctx->task_ctx = NULL;
+        }
+}
+
+#define for_each_task_context_nr(ctxn)                                  \
+        for ((ctxn) = 0; (ctxn) < perf_nr_task_contexts; (ctxn)++)
+
+/*
+ * Called from scheduler to remove the events of the current task,
+ * with interrupts disabled.
+ *
+ * We stop each event and update the event value in event->count.
+ *
+ * This does not protect us against NMI, but disable()
+ * sets the disabled bit in the control field of event _before_
+ * accessing the event control register. If a NMI hits, then it will
+ * not restart the event.
+ */
+void __perf_event_task_sched_out(struct task_struct *task,
+                                 struct task_struct *next)
+{
+        int ctxn;
+
+        for_each_task_context_nr(ctxn)
+                perf_event_context_sched_out(task, ctxn, next);
+
+        /*
+         * if cgroup events exist on this CPU, then we need
+         * to check if we have to switch out PMU state.
+         * cgroup event are system-wide mode only
+         */
+        if (atomic_read(&__get_cpu_var(perf_cgroup_events)))
+                perf_cgroup_sched_out(task);
+}
+
+static void task_ctx_sched_out(struct perf_event_context *ctx,
+                               enum event_type_t event_type)
+{
+        struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+
+        if (!cpuctx->task_ctx)
+                return;
+
+        if (WARN_ON_ONCE(ctx != cpuctx->task_ctx))
+                return;
+
+        ctx_sched_out(ctx, cpuctx, event_type);
+        cpuctx->task_ctx = NULL;
+}
+
+/*
+ * Called with IRQs disabled
+ */
+static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
+                              enum event_type_t event_type)
+{
+        ctx_sched_out(&cpuctx->ctx, cpuctx, event_type);
+}
+
+static void
+ctx_pinned_sched_in(struct perf_event_context *ctx,
+                    struct perf_cpu_context *cpuctx)
+{
+        struct perf_event *event;
+
+        list_for_each_entry(event, &ctx->pinned_groups, group_entry) {
+                if (event->state <= PERF_EVENT_STATE_OFF)
+                        continue;
+                if (!event_filter_match(event))
+                        continue;
+
+                /* may need to reset tstamp_enabled */
+                if (is_cgroup_event(event))
+                        perf_cgroup_mark_enabled(event, ctx);
+
+                if (group_can_go_on(event, cpuctx, 1))
+                        group_sched_in(event, cpuctx, ctx);
+
+                /*
+                 * If this pinned group hasn't been scheduled,
+                 * put it in error state.
+                 */
+                if (event->state == PERF_EVENT_STATE_INACTIVE) {
+                        update_group_times(event);
+                        event->state = PERF_EVENT_STATE_ERROR;
+                }
+        }
+}
+
+static void
+ctx_flexible_sched_in(struct perf_event_context *ctx,
+                      struct perf_cpu_context *cpuctx)
+{
+        struct perf_event *event;
+        int can_add_hw = 1;
+
+        list_for_each_entry(event, &ctx->flexible_groups, group_entry) {
+                /* Ignore events in OFF or ERROR state */
+                if (event->state <= PERF_EVENT_STATE_OFF)
+                        continue;
+                /*
+                 * Listen to the 'cpu' scheduling filter constraint
+                 * of events:
+                 */
+                if (!event_filter_match(event))
+                        continue;
+
+                /* may need to reset tstamp_enabled */
+                if (is_cgroup_event(event))
+                        perf_cgroup_mark_enabled(event, ctx);
+
+                if (group_can_go_on(event, cpuctx, can_add_hw)) {
+                        if (group_sched_in(event, cpuctx, ctx))
+                                can_add_hw = 0;
+                }
+        }
+}
+
+static void
+ctx_sched_in(struct perf_event_context *ctx,
+             struct perf_cpu_context *cpuctx,
+             enum event_type_t event_type,
+             struct task_struct *task)
+{
+        u64 now;
+
+        raw_spin_lock(&ctx->lock);
+        ctx->is_active = 1;
+        if (likely(!ctx->nr_events))
+                goto out;
+
+        now = perf_clock();
+        ctx->timestamp = now;
+        perf_cgroup_set_timestamp(task, ctx);
+        /*
+         * First go through the list and put on any pinned groups
+         * in order to give them the best chance of going on.
+         */
+        if (event_type & EVENT_PINNED)
+                ctx_pinned_sched_in(ctx, cpuctx);
+
+        /* Then walk through the lower prio flexible groups */
+        if (event_type & EVENT_FLEXIBLE)
+                ctx_flexible_sched_in(ctx, cpuctx);
+
+out:
+        raw_spin_unlock(&ctx->lock);
+}
+
+static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
+                             enum event_type_t event_type,
+                             struct task_struct *task)
+{
+        struct perf_event_context *ctx = &cpuctx->ctx;
+
+        ctx_sched_in(ctx, cpuctx, event_type, task);
+}
+
+static void task_ctx_sched_in(struct perf_event_context *ctx,
+                              enum event_type_t event_type)
+{
+        struct perf_cpu_context *cpuctx;
+
+        cpuctx = __get_cpu_context(ctx);
+        if (cpuctx->task_ctx == ctx)
+                return;
+
+        ctx_sched_in(ctx, cpuctx, event_type, NULL);
+        cpuctx->task_ctx = ctx;
+}
+
+static void perf_event_context_sched_in(struct perf_event_context *ctx,
+                                        struct task_struct *task)
+{
+        struct perf_cpu_context *cpuctx;
+
+        cpuctx = __get_cpu_context(ctx);
+        if (cpuctx->task_ctx == ctx)
+                return;
+
+        perf_pmu_disable(ctx->pmu);
+        /*
+         * We want to keep the following priority order:
+         * cpu pinned (that don't need to move), task pinned,
+         * cpu flexible, task flexible.
+         */
+        cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
+
+        ctx_sched_in(ctx, cpuctx, EVENT_PINNED, task);
+        cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE, task);
+        ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE, task);
+
+        cpuctx->task_ctx = ctx;
+
+        /*
+         * Since these rotations are per-cpu, we need to ensure the
+         * cpu-context we got scheduled on is actually rotating.
+         */
+        perf_pmu_rotate_start(ctx->pmu);
+        perf_pmu_enable(ctx->pmu);
+}
+
+/*
+ * Called from scheduler to add the events of the current task
+ * with interrupts disabled.
+ *
+ * We restore the event value and then enable it.
+ *
+ * This does not protect us against NMI, but enable()
+ * sets the enabled bit in the control field of event _before_
+ * accessing the event control register. If a NMI hits, then it will
+ * keep the event running.
+ */
+void __perf_event_task_sched_in(struct task_struct *task)
+{
+        struct perf_event_context *ctx;
+        int ctxn;
+
+        for_each_task_context_nr(ctxn) {
+                ctx = task->perf_event_ctxp[ctxn];
+                if (likely(!ctx))
+                        continue;
+
+                perf_event_context_sched_in(ctx, task);
+        }
+        /*
+         * if cgroup events exist on this CPU, then we need
+         * to check if we have to switch in PMU state.
+         * cgroup event are system-wide mode only
+         */
+        if (atomic_read(&__get_cpu_var(perf_cgroup_events)))
+                perf_cgroup_sched_in(task);
+}
+
+static u64 perf_calculate_period(struct perf_event *event, u64 nsec, u64 count)
+{
+        u64 frequency = event->attr.sample_freq;
+        u64 sec = NSEC_PER_SEC;
+        u64 divisor, dividend;
+
+        int count_fls, nsec_fls, frequency_fls, sec_fls;
+
+        count_fls = fls64(count);
+        nsec_fls = fls64(nsec);
+        frequency_fls = fls64(frequency);
+        sec_fls = 30;
+
+        /*
+         * We got @count in @nsec, with a target of sample_freq HZ
+         * the target period becomes:
+         *
+         *             @count * 10^9
+         * period = -------------------
+         *          @nsec * sample_freq
+         *
+         */
+
+        /*
+         * Reduce accuracy by one bit such that @a and @b converge
+         * to a similar magnitude.
+         */
+#define REDUCE_FLS(a, b)                \
+do {                                    \
+        if (a##_fls > b##_fls) {        \
+                a >>= 1;                \
+                a##_fls--;              \
+        } else {                        \
+                b >>= 1;                \
+                b##_fls--;              \
+        }                               \
+} while (0)
+
+        /*
+         * Reduce accuracy until either term fits in a u64, then proceed with
+         * the other, so that finally we can do a u64/u64 division.
+         */
+        while (count_fls + sec_fls > 64 && nsec_fls + frequency_fls > 64) {
+                REDUCE_FLS(nsec, frequency);
+                REDUCE_FLS(sec, count);
+        }
+
+        if (count_fls + sec_fls > 64) {
+                divisor = nsec * frequency;
+
+                while (count_fls + sec_fls > 64) {
+                        REDUCE_FLS(count, sec);
+                        divisor >>= 1;
+                }
+
+                dividend = count * sec;
+        } else {
+                dividend = count * sec;
+
+                while (nsec_fls + frequency_fls > 64) {
+                        REDUCE_FLS(nsec, frequency);
+                        dividend >>= 1;
+                }
+
+                divisor = nsec * frequency;
+        }
+
+        if (!divisor)
+                return dividend;
+
+        return div64_u64(dividend, divisor);
+}
+
+static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count)
+{
+        struct hw_perf_event *hwc = &event->hw;
+        s64 period, sample_period;
+        s64 delta;
+
+        period = perf_calculate_period(event, nsec, count);
+
+        delta = (s64)(period - hwc->sample_period);
+        delta = (delta + 7) / 8; /* low pass filter */
+
+        sample_period = hwc->sample_period + delta;
+
+        if (!sample_period)
+                sample_period = 1;
+
+        hwc->sample_period = sample_period;
+
+        if (local64_read(&hwc->period_left) > 8*sample_period) {
+                event->pmu->stop(event, PERF_EF_UPDATE);
+                local64_set(&hwc->period_left, 0);
+                event->pmu->start(event, PERF_EF_RELOAD);
+        }
+}
+
+static void perf_ctx_adjust_freq(struct perf_event_context *ctx, u64 period)
+{
+        struct perf_event *event;
+        struct hw_perf_event *hwc;
+        u64 interrupts, now;
+        s64 delta;
+
+        raw_spin_lock(&ctx->lock);
+        list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
+                if (event->state != PERF_EVENT_STATE_ACTIVE)
+                        continue;
+
+                if (!event_filter_match(event))
+                        continue;
+
+                hwc = &event->hw;
+
+                interrupts = hwc->interrupts;
+                hwc->interrupts = 0;
+
+                /*
+                 * unthrottle events on the tick
+                 */
+                if (interrupts == MAX_INTERRUPTS) {
+                        perf_log_throttle(event, 1);
+                        event->pmu->start(event, 0);
+                }
+
+                if (!event->attr.freq || !event->attr.sample_freq)
+                        continue;
+
+                event->pmu->read(event);
+                now = local64_read(&event->count);
+                delta = now - hwc->freq_count_stamp;
+                hwc->freq_count_stamp = now;
+
+                if (delta > 0)
+                        perf_adjust_period(event, period, delta);
+        }
+        raw_spin_unlock(&ctx->lock);
+}
+
+/*
+ * Round-robin a context's events:
+ */
+static void rotate_ctx(struct perf_event_context *ctx)
+{
+        raw_spin_lock(&ctx->lock);
+
+        /*
+         * Rotate the first entry last of non-pinned groups. Rotation might be
+         * disabled by the inheritance code.
+         */
+        if (!ctx->rotate_disable)
+                list_rotate_left(&ctx->flexible_groups);
+
+        raw_spin_unlock(&ctx->lock);
+}
+
+/*
+ * perf_pmu_rotate_start() and perf_rotate_context() are fully serialized
+ * because they're strictly cpu affine and rotate_start is called with IRQs
+ * disabled, while rotate_context is called from IRQ context.
+ */
+static void perf_rotate_context(struct perf_cpu_context *cpuctx)
+{
+        u64 interval = (u64)cpuctx->jiffies_interval * TICK_NSEC;
+        struct perf_event_context *ctx = NULL;
+        int rotate = 0, remove = 1;
+
+        if (cpuctx->ctx.nr_events) {
+                remove = 0;
+                if (cpuctx->ctx.nr_events != cpuctx->ctx.nr_active)
+                        rotate = 1;
+        }
+
+        ctx = cpuctx->task_ctx;
+        if (ctx && ctx->nr_events) {
+                remove = 0;
+                if (ctx->nr_events != ctx->nr_active)
+                        rotate = 1;
+        }
+
+        perf_pmu_disable(cpuctx->ctx.pmu);
+        perf_ctx_adjust_freq(&cpuctx->ctx, interval);
+        if (ctx)
+                perf_ctx_adjust_freq(ctx, interval);
+
+        if (!rotate)
+                goto done;
+
+        cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
+        if (ctx)
+                task_ctx_sched_out(ctx, EVENT_FLEXIBLE);
+
+        rotate_ctx(&cpuctx->ctx);
+        if (ctx)
+                rotate_ctx(ctx);
+
+        cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE, current);
+        if (ctx)
+                task_ctx_sched_in(ctx, EVENT_FLEXIBLE);
+
+done:
+        if (remove)
+                list_del_init(&cpuctx->rotation_list);
+
+        perf_pmu_enable(cpuctx->ctx.pmu);
+}
+
+void perf_event_task_tick(void)
+{
+        struct list_head *head = &__get_cpu_var(rotation_list);
+        struct perf_cpu_context *cpuctx, *tmp;
+
+        WARN_ON(!irqs_disabled());
+
+        list_for_each_entry_safe(cpuctx, tmp, head, rotation_list) {
+                if (cpuctx->jiffies_interval == 1 ||
+                                !(jiffies % cpuctx->jiffies_interval))
+                        perf_rotate_context(cpuctx);
+        }
+}
+
+static int event_enable_on_exec(struct perf_event *event,
+                                struct perf_event_context *ctx)
+{
+        if (!event->attr.enable_on_exec)
+                return 0;
+
+        event->attr.enable_on_exec = 0;
+        if (event->state >= PERF_EVENT_STATE_INACTIVE)
+                return 0;
+
+        __perf_event_mark_enabled(event, ctx);
+
+        return 1;
+}
+
+/*
+ * Enable all of a task's events that have been marked enable-on-exec.
+ * This expects task == current.
+ */
+static void perf_event_enable_on_exec(struct perf_event_context *ctx)
+{
+        struct perf_event *event;
+        unsigned long flags;
+        int enabled = 0;
+        int ret;
+
+        local_irq_save(flags);
+        if (!ctx || !ctx->nr_events)
+                goto out;
+
+        /*
+         * We must ctxsw out cgroup events to avoid conflict
+         * when invoking perf_task_event_sched_in() later on
+         * in this function. Otherwise we end up trying to
+         * ctxswin cgroup events which are already scheduled
+         * in.
+         */
+        perf_cgroup_sched_out(current);
+        task_ctx_sched_out(ctx, EVENT_ALL);
+
+        raw_spin_lock(&ctx->lock);
+
+        list_for_each_entry(event, &ctx->pinned_groups, group_entry) {
+                ret = event_enable_on_exec(event, ctx);
+                if (ret)
+                        enabled = 1;
+        }
+
+        list_for_each_entry(event, &ctx->flexible_groups, group_entry) {
+                ret = event_enable_on_exec(event, ctx);
+                if (ret)
+                        enabled = 1;
+        }
+
+        /*
+         * Unclone this context if we enabled any event.
+         */
+        if (enabled)
+                unclone_ctx(ctx);
+
+        raw_spin_unlock(&ctx->lock);
+
+        /*
+         * Also calls ctxswin for cgroup events, if any:
+         */
+        perf_event_context_sched_in(ctx, ctx->task);
+out:
+        local_irq_restore(flags);
+}
+
+/*
+ * Cross CPU call to read the hardware event
+ */
+static void __perf_event_read(void *info)
+{
+        struct perf_event *event = info;
+        struct perf_event_context *ctx = event->ctx;
+        struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+
+        /*
+         * If this is a task context, we need to check whether it is
+         * the current task context of this cpu.  If not it has been
+         * scheduled out before the smp call arrived.  In that case
+         * event->count would have been updated to a recent sample
+         * when the event was scheduled out.
+         */
+        if (ctx->task && cpuctx->task_ctx != ctx)
+                return;
+
+        raw_spin_lock(&ctx->lock);
+        if (ctx->is_active) {
+                update_context_time(ctx);
+                update_cgrp_time_from_event(event);
+        }
+        update_event_times(event);
+        if (event->state == PERF_EVENT_STATE_ACTIVE)
+                event->pmu->read(event);
+        raw_spin_unlock(&ctx->lock);
+}
+
+static inline u64 perf_event_count(struct perf_event *event)
+{
+        return local64_read(&event->count) + atomic64_read(&event->child_count);
+}
+
+static u64 perf_event_read(struct perf_event *event)
+{
+        /*
+         * If event is enabled and currently active on a CPU, update the
+         * value in the event structure:
+         */
+        if (event->state == PERF_EVENT_STATE_ACTIVE) {
+                smp_call_function_single(event->oncpu,
+                                         __perf_event_read, event, 1);
+        } else if (event->state == PERF_EVENT_STATE_INACTIVE) {
+                struct perf_event_context *ctx = event->ctx;
+                unsigned long flags;
+
+                raw_spin_lock_irqsave(&ctx->lock, flags);
+                /*
+                 * may read while context is not active
+                 * (e.g., thread is blocked), in that case
+                 * we cannot update context time
+                 */
+                if (ctx->is_active) {
+                        update_context_time(ctx);
+                        update_cgrp_time_from_event(event);
+                }
+                update_event_times(event);
+                raw_spin_unlock_irqrestore(&ctx->lock, flags);
+        }
+
+        return perf_event_count(event);
+}
+
+/*
+ * Callchain support
+ */
+
+struct callchain_cpus_entries {
+        struct rcu_head                 rcu_head;
+        struct perf_callchain_entry     *cpu_entries[0];
+};
+
+static DEFINE_PER_CPU(int, callchain_recursion[PERF_NR_CONTEXTS]);
+static atomic_t nr_callchain_events;
+static DEFINE_MUTEX(callchain_mutex);
+struct callchain_cpus_entries *callchain_cpus_entries;
+
+
+__weak void perf_callchain_kernel(struct perf_callchain_entry *entry,
+                                  struct pt_regs *regs)
+{
+}
+
+__weak void perf_callchain_user(struct perf_callchain_entry *entry,
+                                struct pt_regs *regs)
+{
+}
+
+static void release_callchain_buffers_rcu(struct rcu_head *head)
+{
+        struct callchain_cpus_entries *entries;
+        int cpu;
+
+        entries = container_of(head, struct callchain_cpus_entries, rcu_head);
+
+        for_each_possible_cpu(cpu)
+                kfree(entries->cpu_entries[cpu]);
+
+        kfree(entries);
+}
+
+static void release_callchain_buffers(void)
+{
+        struct callchain_cpus_entries *entries;
+
+        entries = callchain_cpus_entries;
+        rcu_assign_pointer(callchain_cpus_entries, NULL);
+        call_rcu(&entries->rcu_head, release_callchain_buffers_rcu);
+}
+
+static int alloc_callchain_buffers(void)
+{
+        int cpu;
+        int size;
+        struct callchain_cpus_entries *entries;
+
+        /*
+         * We can't use the percpu allocation API for data that can be
+         * accessed from NMI. Use a temporary manual per cpu allocation
+         * until that gets sorted out.
+         */
+        size = offsetof(struct callchain_cpus_entries, cpu_entries[nr_cpu_ids]);
+
+        entries = kzalloc(size, GFP_KERNEL);
+        if (!entries)
+                return -ENOMEM;
+
+        size = sizeof(struct perf_callchain_entry) * PERF_NR_CONTEXTS;
+
+        for_each_possible_cpu(cpu) {
+                entries->cpu_entries[cpu] = kmalloc_node(size, GFP_KERNEL,
+                                                         cpu_to_node(cpu));
+                if (!entries->cpu_entries[cpu])
+                        goto fail;
+        }
+
+        rcu_assign_pointer(callchain_cpus_entries, entries);
+
+        return 0;
+
+fail:
+        for_each_possible_cpu(cpu)
+                kfree(entries->cpu_entries[cpu]);
+        kfree(entries);
+
+        return -ENOMEM;
+}
+
+static int get_callchain_buffers(void)
+{
+        int err = 0;
+        int count;
+
+        mutex_lock(&callchain_mutex);
+
+        count = atomic_inc_return(&nr_callchain_events);
+        if (WARN_ON_ONCE(count < 1)) {
+                err = -EINVAL;
+                goto exit;
+        }
+
+        if (count > 1) {
+                /* If the allocation failed, give up */
+                if (!callchain_cpus_entries)
+                        err = -ENOMEM;
+                goto exit;
+        }
+
+        err = alloc_callchain_buffers();
+        if (err)
+                release_callchain_buffers();
+exit:
+        mutex_unlock(&callchain_mutex);
+
+        return err;
+}
+
+static void put_callchain_buffers(void)
+{
+        if (atomic_dec_and_mutex_lock(&nr_callchain_events, &callchain_mutex)) {
+                release_callchain_buffers();
+                mutex_unlock(&callchain_mutex);
+        }
+}
+
+static int get_recursion_context(int *recursion)
+{
+        int rctx;
+
+        if (in_nmi())
+                rctx = 3;
+        else if (in_irq())
+                rctx = 2;
+        else if (in_softirq())
+                rctx = 1;
+        else
+                rctx = 0;
+
+        if (recursion[rctx])
+                return -1;
+
+        recursion[rctx]++;
+        barrier();
+
+        return rctx;
+}
+
+static inline void put_recursion_context(int *recursion, int rctx)
+{
+        barrier();
+        recursion[rctx]--;
+}
+
+static struct perf_callchain_entry *get_callchain_entry(int *rctx)
+{
+        int cpu;
+        struct callchain_cpus_entries *entries;
+
+        *rctx = get_recursion_context(__get_cpu_var(callchain_recursion));
+        if (*rctx == -1)
+                return NULL;
+
+        entries = rcu_dereference(callchain_cpus_entries);
+        if (!entries)
+                return NULL;
+
+        cpu = smp_processor_id();
+
+        return &entries->cpu_entries[cpu][*rctx];
+}
+
+static void
+put_callchain_entry(int rctx)
+{
+        put_recursion_context(__get_cpu_var(callchain_recursion), rctx);
+}
+
+static struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
+{
+        int rctx;
+        struct perf_callchain_entry *entry;
+
+
+        entry = get_callchain_entry(&rctx);
+        if (rctx == -1)
+                return NULL;
+
+        if (!entry)
+                goto exit_put;
+
+        entry->nr = 0;
+
+        if (!user_mode(regs)) {
+                perf_callchain_store(entry, PERF_CONTEXT_KERNEL);
+                perf_callchain_kernel(entry, regs);
+                if (current->mm)
+                        regs = task_pt_regs(current);
+                else
+                        regs = NULL;
+        }
+
+        if (regs) {
+                perf_callchain_store(entry, PERF_CONTEXT_USER);
+                perf_callchain_user(entry, regs);
+        }
+
+exit_put:
+        put_callchain_entry(rctx);
+
+        return entry;
+}
+
+/*
+ * Initialize the perf_event context in a task_struct:
+ */
+static void __perf_event_init_context(struct perf_event_context *ctx)
+{
+        raw_spin_lock_init(&ctx->lock);
+        mutex_init(&ctx->mutex);
+        INIT_LIST_HEAD(&ctx->pinned_groups);
+        INIT_LIST_HEAD(&ctx->flexible_groups);
+        INIT_LIST_HEAD(&ctx->event_list);
+        atomic_set(&ctx->refcount, 1);
+}
+
+static struct perf_event_context *
+alloc_perf_context(struct pmu *pmu, struct task_struct *task)
+{
+        struct perf_event_context *ctx;
+
+        ctx = kzalloc(sizeof(struct perf_event_context), GFP_KERNEL);
+        if (!ctx)
+                return NULL;
+
+        __perf_event_init_context(ctx);
+        if (task) {
+                ctx->task = task;
+                get_task_struct(task);
+        }
+        ctx->pmu = pmu;
+
+        return ctx;
+}
+
+static struct task_struct *
+find_lively_task_by_vpid(pid_t vpid)
+{
+        struct task_struct *task;
+        int err;
+
+        rcu_read_lock();
+        if (!vpid)
+                task = current;
+        else
+                task = find_task_by_vpid(vpid);
+        if (task)
+                get_task_struct(task);
+        rcu_read_unlock();
+
+        if (!task)
+                return ERR_PTR(-ESRCH);
+
+        /* Reuse ptrace permission checks for now. */
+        err = -EACCES;
+        if (!ptrace_may_access(task, PTRACE_MODE_READ))
+                goto errout;
+
+        return task;
+errout:
+        put_task_struct(task);
+        return ERR_PTR(err);
+
+}
+
+/*
+ * Returns a matching context with refcount and pincount.
+ */
+static struct perf_event_context *
+find_get_context(struct pmu *pmu, struct task_struct *task, int cpu)
+{
+        struct perf_event_context *ctx;
+        struct perf_cpu_context *cpuctx;
+        unsigned long flags;
+        int ctxn, err;
+
+        if (!task) {
+                /* Must be root to operate on a CPU event: */
+                if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
+                        return ERR_PTR(-EACCES);
+
+                /*
+                 * We could be clever and allow to attach a event to an
+                 * offline CPU and activate it when the CPU comes up, but
+                 * that's for later.
+                 */
+                if (!cpu_online(cpu))
+                        return ERR_PTR(-ENODEV);
+
+                cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+                ctx = &cpuctx->ctx;
+                get_ctx(ctx);
+                ++ctx->pin_count;
+
+                return ctx;
+        }
+
+        err = -EINVAL;
+        ctxn = pmu->task_ctx_nr;
+        if (ctxn < 0)
+                goto errout;
+
+retry:
+        ctx = perf_lock_task_context(task, ctxn, &flags);
+        if (ctx) {
+                unclone_ctx(ctx);
+                ++ctx->pin_count;
+                raw_spin_unlock_irqrestore(&ctx->lock, flags);
+        }
+
+        if (!ctx) {
+                ctx = alloc_perf_context(pmu, task);
+                err = -ENOMEM;
+                if (!ctx)
+                        goto errout;
+
+                get_ctx(ctx);
+
+                err = 0;
+                mutex_lock(&task->perf_event_mutex);
+                /*
+                 * If it has already passed perf_event_exit_task().
+                 * we must see PF_EXITING, it takes this mutex too.
+                 */
+                if (task->flags & PF_EXITING)
+                        err = -ESRCH;
+                else if (task->perf_event_ctxp[ctxn])
+                        err = -EAGAIN;
+                else {
+                        ++ctx->pin_count;
+                        rcu_assign_pointer(task->perf_event_ctxp[ctxn], ctx);
+                }
+                mutex_unlock(&task->perf_event_mutex);
+
+                if (unlikely(err)) {
+                        put_task_struct(task);
+                        kfree(ctx);
+
+                        if (err == -EAGAIN)
+                                goto retry;
+                        goto errout;
+                }
+        }
+
+        return ctx;
+
+errout:
+        return ERR_PTR(err);
+}
+
+static void perf_event_free_filter(struct perf_event *event);
+
+static void free_event_rcu(struct rcu_head *head)
+{
+        struct perf_event *event;
+
+        event = container_of(head, struct perf_event, rcu_head);
+        if (event->ns)
+                put_pid_ns(event->ns);
+        perf_event_free_filter(event);
+        kfree(event);
+}
+
+static void perf_buffer_put(struct perf_buffer *buffer);
+
+static void free_event(struct perf_event *event)
+{
+        irq_work_sync(&event->pending);
+
+        if (!event->parent) {
+                if (event->attach_state & PERF_ATTACH_TASK)
+                        jump_label_dec(&perf_sched_events);
+                if (event->attr.mmap || event->attr.mmap_data)
+                        atomic_dec(&nr_mmap_events);
+                if (event->attr.comm)
+                        atomic_dec(&nr_comm_events);
+                if (event->attr.task)
+                        atomic_dec(&nr_task_events);
+                if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
+                        put_callchain_buffers();
+                if (is_cgroup_event(event)) {
+                        atomic_dec(&per_cpu(perf_cgroup_events, event->cpu));
+                        jump_label_dec(&perf_sched_events);
+                }
+        }
+
+        if (event->buffer) {
+                perf_buffer_put(event->buffer);
+                event->buffer = NULL;
+        }
+
+        if (is_cgroup_event(event))
+                perf_detach_cgroup(event);
+
+        if (event->destroy)
+                event->destroy(event);
+
+        if (event->ctx)
+                put_ctx(event->ctx);
+
+        call_rcu(&event->rcu_head, free_event_rcu);
+}
+
+int perf_event_release_kernel(struct perf_event *event)
+{
+        struct perf_event_context *ctx = event->ctx;
+
+        /*
+         * Remove from the PMU, can't get re-enabled since we got
+         * here because the last ref went.
+         */
+        perf_event_disable(event);
+
+        WARN_ON_ONCE(ctx->parent_ctx);
+        /*
+         * There are two ways this annotation is useful:
+         *
+         *  1) there is a lock recursion from perf_event_exit_task
+         *     see the comment there.
+         *
+         *  2) there is a lock-inversion with mmap_sem through
+         *     perf_event_read_group(), which takes faults while
+         *     holding ctx->mutex, however this is called after
+         *     the last filedesc died, so there is no possibility
+         *     to trigger the AB-BA case.
+         */
+        mutex_lock_nested(&ctx->mutex, SINGLE_DEPTH_NESTING);
+        raw_spin_lock_irq(&ctx->lock);
+        perf_group_detach(event);
+        list_del_event(event, ctx);
+        raw_spin_unlock_irq(&ctx->lock);
+        mutex_unlock(&ctx->mutex);
+
+        free_event(event);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(perf_event_release_kernel);
+
+/*
+ * Called when the last reference to the file is gone.
+ */
+static int perf_release(struct inode *inode, struct file *file)
+{
+        struct perf_event *event = file->private_data;
+        struct task_struct *owner;
+
+        file->private_data = NULL;
+
+        rcu_read_lock();
+        owner = ACCESS_ONCE(event->owner);
+        /*
+         * Matches the smp_wmb() in perf_event_exit_task(). If we observe
+         * !owner it means the list deletion is complete and we can indeed
+         * free this event, otherwise we need to serialize on
+         * owner->perf_event_mutex.
+         */
+        smp_read_barrier_depends();
+        if (owner) {
+                /*
+                 * Since delayed_put_task_struct() also drops the last
+                 * task reference we can safely take a new reference
+                 * while holding the rcu_read_lock().
+                 */
+                get_task_struct(owner);
+        }
+        rcu_read_unlock();
+
+        if (owner) {
+                mutex_lock(&owner->perf_event_mutex);
+                /*
+                 * We have to re-check the event->owner field, if it is cleared
+                 * we raced with perf_event_exit_task(), acquiring the mutex
+                 * ensured they're done, and we can proceed with freeing the
+                 * event.
+                 */
+                if (event->owner)
+                        list_del_init(&event->owner_entry);
+                mutex_unlock(&owner->perf_event_mutex);
+                put_task_struct(owner);
+        }
+
+        return perf_event_release_kernel(event);
+}
+
+u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
+{
+        struct perf_event *child;
+        u64 total = 0;
+
+        *enabled = 0;
+        *running = 0;
+
+        mutex_lock(&event->child_mutex);
+        total += perf_event_read(event);
+        *enabled += event->total_time_enabled +
+                        atomic64_read(&event->child_total_time_enabled);
+        *running += event->total_time_running +
+                        atomic64_read(&event->child_total_time_running);
+
+        list_for_each_entry(child, &event->child_list, child_list) {
+                total += perf_event_read(child);
+                *enabled += child->total_time_enabled;
+                *running += child->total_time_running;
+        }
+        mutex_unlock(&event->child_mutex);
+
+        return total;
+}
+EXPORT_SYMBOL_GPL(perf_event_read_value);
+
+static int perf_event_read_group(struct perf_event *event,
+                                   u64 read_format, char __user *buf)
+{
+        struct perf_event *leader = event->group_leader, *sub;
+        int n = 0, size = 0, ret = -EFAULT;
+        struct perf_event_context *ctx = leader->ctx;
+        u64 values[5];
+        u64 count, enabled, running;
+
+        mutex_lock(&ctx->mutex);
+        count = perf_event_read_value(leader, &enabled, &running);
+
+        values[n++] = 1 + leader->nr_siblings;
+        if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+                values[n++] = enabled;
+        if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+                values[n++] = running;
+        values[n++] = count;
+        if (read_format & PERF_FORMAT_ID)
+                values[n++] = primary_event_id(leader);
+
+        size = n * sizeof(u64);
+
+        if (copy_to_user(buf, values, size))
+                goto unlock;
+
+        ret = size;
+
+        list_for_each_entry(sub, &leader->sibling_list, group_entry) {
+                n = 0;
+
+                values[n++] = perf_event_read_value(sub, &enabled, &running);
+                if (read_format & PERF_FORMAT_ID)
+                        values[n++] = primary_event_id(sub);
+
+                size = n * sizeof(u64);
+
+                if (copy_to_user(buf + ret, values, size)) {
+                        ret = -EFAULT;
+                        goto unlock;
+                }
+
+                ret += size;
+        }
+unlock:
+        mutex_unlock(&ctx->mutex);
+
+        return ret;
+}
+
+static int perf_event_read_one(struct perf_event *event,
+                                 u64 read_format, char __user *buf)
+{
+        u64 enabled, running;
+        u64 values[4];
+        int n = 0;
+
+        values[n++] = perf_event_read_value(event, &enabled, &running);
+        if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+                values[n++] = enabled;
+        if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+                values[n++] = running;
+        if (read_format & PERF_FORMAT_ID)
+                values[n++] = primary_event_id(event);
+
+        if (copy_to_user(buf, values, n * sizeof(u64)))
+                return -EFAULT;
+
+        return n * sizeof(u64);
+}
+
+/*
+ * Read the performance event - simple non blocking version for now
+ */
+static ssize_t
+perf_read_hw(struct perf_event *event, char __user *buf, size_t count)
+{
+        u64 read_format = event->attr.read_format;
+        int ret;
+
+        /*
+         * Return end-of-file for a read on a event that is in
+         * error state (i.e. because it was pinned but it couldn't be
+         * scheduled on to the CPU at some point).
+         */
+        if (event->state == PERF_EVENT_STATE_ERROR)
+                return 0;
+
+        if (count < event->read_size)
+                return -ENOSPC;
+
+        WARN_ON_ONCE(event->ctx->parent_ctx);
+        if (read_format & PERF_FORMAT_GROUP)
+                ret = perf_event_read_group(event, read_format, buf);
+        else
+                ret = perf_event_read_one(event, read_format, buf);
+
+        return ret;
+}
+
+static ssize_t
+perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+        struct perf_event *event = file->private_data;
+
+        return perf_read_hw(event, buf, count);
+}
+
+static unsigned int perf_poll(struct file *file, poll_table *wait)
+{
+        struct perf_event *event = file->private_data;
+        struct perf_buffer *buffer;
+        unsigned int events = POLL_HUP;
+
+        rcu_read_lock();
+        buffer = rcu_dereference(event->buffer);
+        if (buffer)
+                events = atomic_xchg(&buffer->poll, 0);
+        rcu_read_unlock();
+
+        poll_wait(file, &event->waitq, wait);
+
+        return events;
+}
+
+static void perf_event_reset(struct perf_event *event)
+{
+        (void)perf_event_read(event);
+        local64_set(&event->count, 0);
+        perf_event_update_userpage(event);
+}
+
+/*
+ * Holding the top-level event's child_mutex means that any
+ * descendant process that has inherited this event will block
+ * in sync_child_event if it goes to exit, thus satisfying the
+ * task existence requirements of perf_event_enable/disable.
+ */
+static void perf_event_for_each_child(struct perf_event *event,
+                                        void (*func)(struct perf_event *))
+{
+        struct perf_event *child;
+
+        WARN_ON_ONCE(event->ctx->parent_ctx);
+        mutex_lock(&event->child_mutex);
+        func(event);
+        list_for_each_entry(child, &event->child_list, child_list)
+                func(child);
+        mutex_unlock(&event->child_mutex);
+}
+
+static void perf_event_for_each(struct perf_event *event,
+                                  void (*func)(struct perf_event *))
+{
+        struct perf_event_context *ctx = event->ctx;
+        struct perf_event *sibling;
+
+        WARN_ON_ONCE(ctx->parent_ctx);
+        mutex_lock(&ctx->mutex);
+        event = event->group_leader;
+
+        perf_event_for_each_child(event, func);
+        func(event);
+        list_for_each_entry(sibling, &event->sibling_list, group_entry)
+                perf_event_for_each_child(event, func);
+        mutex_unlock(&ctx->mutex);
+}
+
+static int perf_event_period(struct perf_event *event, u64 __user *arg)
+{
+        struct perf_event_context *ctx = event->ctx;
+        int ret = 0;
+        u64 value;
+
+        if (!is_sampling_event(event))
+                return -EINVAL;
+
+        if (copy_from_user(&value, arg, sizeof(value)))
+                return -EFAULT;
+
+        if (!value)
+                return -EINVAL;
+
+        raw_spin_lock_irq(&ctx->lock);
+        if (event->attr.freq) {
+                if (value > sysctl_perf_event_sample_rate) {
+                        ret = -EINVAL;
+                        goto unlock;
+                }
+
+                event->attr.sample_freq = value;
+        } else {
+                event->attr.sample_period = value;
+                event->hw.sample_period = value;
+        }
+unlock:
+        raw_spin_unlock_irq(&ctx->lock);
+
+        return ret;
+}
+
+static const struct file_operations perf_fops;
+
+static struct perf_event *perf_fget_light(int fd, int *fput_needed)
+{
+        struct file *file;
+
+        file = fget_light(fd, fput_needed);
+        if (!file)
+                return ERR_PTR(-EBADF);
+
+        if (file->f_op != &perf_fops) {
+                fput_light(file, *fput_needed);
+                *fput_needed = 0;
+                return ERR_PTR(-EBADF);
+        }
+
+        return file->private_data;
+}
+
+static int perf_event_set_output(struct perf_event *event,
+                                 struct perf_event *output_event);
+static int perf_event_set_filter(struct perf_event *event, void __user *arg);
+
+static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+        struct perf_event *event = file->private_data;
+        void (*func)(struct perf_event *);
+        u32 flags = arg;
+
+        switch (cmd) {
+        case PERF_EVENT_IOC_ENABLE:
+                func = perf_event_enable;
+                break;
+        case PERF_EVENT_IOC_DISABLE:
+                func = perf_event_disable;
+                break;
+        case PERF_EVENT_IOC_RESET:
+                func = perf_event_reset;
+                break;
+
+        case PERF_EVENT_IOC_REFRESH:
+                return perf_event_refresh(event, arg);
+
+        case PERF_EVENT_IOC_PERIOD:
+                return perf_event_period(event, (u64 __user *)arg);
+
+        case PERF_EVENT_IOC_SET_OUTPUT:
+        {
+                struct perf_event *output_event = NULL;
+                int fput_needed = 0;
+                int ret;
+
+                if (arg != -1) {
+                        output_event = perf_fget_light(arg, &fput_needed);
+                        if (IS_ERR(output_event))
+                                return PTR_ERR(output_event);
+                }
+
+                ret = perf_event_set_output(event, output_event);
+                if (output_event)
+                        fput_light(output_event->filp, fput_needed);
+
+                return ret;
+        }
+
+        case PERF_EVENT_IOC_SET_FILTER:
+                return perf_event_set_filter(event, (void __user *)arg);
+
+        default:
+                return -ENOTTY;
+        }
+
+        if (flags & PERF_IOC_FLAG_GROUP)
+                perf_event_for_each(event, func);
+        else
+                perf_event_for_each_child(event, func);
+
+        return 0;
+}
+
+int perf_event_task_enable(void)
+{
+        struct perf_event *event;
+
+        mutex_lock(&current->perf_event_mutex);
+        list_for_each_entry(event, &current->perf_event_list, owner_entry)
+                perf_event_for_each_child(event, perf_event_enable);
+        mutex_unlock(&current->perf_event_mutex);
+
+        return 0;
+}
+
+int perf_event_task_disable(void)
+{
+        struct perf_event *event;
+
+        mutex_lock(&current->perf_event_mutex);
+        list_for_each_entry(event, &current->perf_event_list, owner_entry)
+                perf_event_for_each_child(event, perf_event_disable);
+        mutex_unlock(&current->perf_event_mutex);
+
+        return 0;
+}
+
+#ifndef PERF_EVENT_INDEX_OFFSET
+# define PERF_EVENT_INDEX_OFFSET 0
+#endif
+
+static int perf_event_index(struct perf_event *event)
+{
+        if (event->hw.state & PERF_HES_STOPPED)
+                return 0;
+
+        if (event->state != PERF_EVENT_STATE_ACTIVE)
+                return 0;
+
+        return event->hw.idx + 1 - PERF_EVENT_INDEX_OFFSET;
+}
+
+/*
+ * Callers need to ensure there can be no nesting of this function, otherwise
+ * the seqlock logic goes bad. We can not serialize this because the arch
+ * code calls this from NMI context.
+ */
+void perf_event_update_userpage(struct perf_event *event)
+{
+        struct perf_event_mmap_page *userpg;
+        struct perf_buffer *buffer;
+
+        rcu_read_lock();
+        buffer = rcu_dereference(event->buffer);
+        if (!buffer)
+                goto unlock;
+
+        userpg = buffer->user_page;
+
+        /*
+         * Disable preemption so as to not let the corresponding user-space
+         * spin too long if we get preempted.
+         */
+        preempt_disable();
+        ++userpg->lock;
+        barrier();
+        userpg->index = perf_event_index(event);
+        userpg->offset = perf_event_count(event);
+        if (event->state == PERF_EVENT_STATE_ACTIVE)
+                userpg->offset -= local64_read(&event->hw.prev_count);
+
+        userpg->time_enabled = event->total_time_enabled +
+                        atomic64_read(&event->child_total_time_enabled);
+
+        userpg->time_running = event->total_time_running +
+                        atomic64_read(&event->child_total_time_running);
+
+        barrier();
+        ++userpg->lock;
+        preempt_enable();
+unlock:
+        rcu_read_unlock();
+}
+
+static unsigned long perf_data_size(struct perf_buffer *buffer);
+
+static void
+perf_buffer_init(struct perf_buffer *buffer, long watermark, int flags)
+{
+        long max_size = perf_data_size(buffer);
+
+        if (watermark)
+                buffer->watermark = min(max_size, watermark);
+
+        if (!buffer->watermark)
+                buffer->watermark = max_size / 2;
+
+        if (flags & PERF_BUFFER_WRITABLE)
+                buffer->writable = 1;
+
+        atomic_set(&buffer->refcount, 1);
+}
+
+#ifndef CONFIG_PERF_USE_VMALLOC
+
+/*
+ * Back perf_mmap() with regular GFP_KERNEL-0 pages.
+ */
+
+static struct page *
+perf_mmap_to_page(struct perf_buffer *buffer, unsigned long pgoff)
+{
+        if (pgoff > buffer->nr_pages)
+                return NULL;
+
+        if (pgoff == 0)
+                return virt_to_page(buffer->user_page);
+
+        return virt_to_page(buffer->data_pages[pgoff - 1]);
+}
+
+static void *perf_mmap_alloc_page(int cpu)
+{
+        struct page *page;
+        int node;
+
+        node = (cpu == -1) ? cpu : cpu_to_node(cpu);
+        page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
+        if (!page)
+                return NULL;
+
+        return page_address(page);
+}
+
+static struct perf_buffer *
+perf_buffer_alloc(int nr_pages, long watermark, int cpu, int flags)
+{
+        struct perf_buffer *buffer;
+        unsigned long size;
+        int i;
+
+        size = sizeof(struct perf_buffer);
+        size += nr_pages * sizeof(void *);
+
+        buffer = kzalloc(size, GFP_KERNEL);
+        if (!buffer)
+                goto fail;
+
+        buffer->user_page = perf_mmap_alloc_page(cpu);
+        if (!buffer->user_page)
+                goto fail_user_page;
+
+        for (i = 0; i < nr_pages; i++) {
+                buffer->data_pages[i] = perf_mmap_alloc_page(cpu);
+                if (!buffer->data_pages[i])
+                        goto fail_data_pages;
+        }
+
+        buffer->nr_pages = nr_pages;
+
+        perf_buffer_init(buffer, watermark, flags);
+
+        return buffer;
+
+fail_data_pages:
+        for (i--; i >= 0; i--)
+                free_page((unsigned long)buffer->data_pages[i]);
+
+        free_page((unsigned long)buffer->user_page);
+
+fail_user_page:
+        kfree(buffer);
+
+fail:
+        return NULL;
+}
+
+static void perf_mmap_free_page(unsigned long addr)
+{
+        struct page *page = virt_to_page((void *)addr);
+
+        page->mapping = NULL;
+        __free_page(page);
+}
+
+static void perf_buffer_free(struct perf_buffer *buffer)
+{
+        int i;
+
+        perf_mmap_free_page((unsigned long)buffer->user_page);
+        for (i = 0; i < buffer->nr_pages; i++)
+                perf_mmap_free_page((unsigned long)buffer->data_pages[i]);
+        kfree(buffer);
+}
+
+static inline int page_order(struct perf_buffer *buffer)
+{
+        return 0;
+}
+
+#else
+
+/*
+ * Back perf_mmap() with vmalloc memory.
+ *
+ * Required for architectures that have d-cache aliasing issues.
+ */
+
+static inline int page_order(struct perf_buffer *buffer)
+{
+        return buffer->page_order;
+}
+
+static struct page *
+perf_mmap_to_page(struct perf_buffer *buffer, unsigned long pgoff)
+{
+        if (pgoff > (1UL << page_order(buffer)))
+                return NULL;
+
+        return vmalloc_to_page((void *)buffer->user_page + pgoff * PAGE_SIZE);
+}
+
+static void perf_mmap_unmark_page(void *addr)
+{
+        struct page *page = vmalloc_to_page(addr);
+
+        page->mapping = NULL;
+}
+
+static void perf_buffer_free_work(struct work_struct *work)
+{
+        struct perf_buffer *buffer;
+        void *base;
+        int i, nr;
+
+        buffer = container_of(work, struct perf_buffer, work);
+        nr = 1 << page_order(buffer);
+
+        base = buffer->user_page;
+        for (i = 0; i < nr + 1; i++)
+                perf_mmap_unmark_page(base + (i * PAGE_SIZE));
+
+        vfree(base);
+        kfree(buffer);
+}
+
+static void perf_buffer_free(struct perf_buffer *buffer)
+{
+        schedule_work(&buffer->work);
+}
+
+static struct perf_buffer *
+perf_buffer_alloc(int nr_pages, long watermark, int cpu, int flags)
+{
+        struct perf_buffer *buffer;
+        unsigned long size;
+        void *all_buf;
+
+        size = sizeof(struct perf_buffer);
+        size += sizeof(void *);
+
+        buffer = kzalloc(size, GFP_KERNEL);
+        if (!buffer)
+                goto fail;
+
+        INIT_WORK(&buffer->work, perf_buffer_free_work);
+
+        all_buf = vmalloc_user((nr_pages + 1) * PAGE_SIZE);
+        if (!all_buf)
+                goto fail_all_buf;
+
+        buffer->user_page = all_buf;
+        buffer->data_pages[0] = all_buf + PAGE_SIZE;
+        buffer->page_order = ilog2(nr_pages);
+        buffer->nr_pages = 1;
+
+        perf_buffer_init(buffer, watermark, flags);
+
+        return buffer;
+
+fail_all_buf:
+        kfree(buffer);
+
+fail:
+        return NULL;
+}
+
+#endif
+
+static unsigned long perf_data_size(struct perf_buffer *buffer)
+{
+        return buffer->nr_pages << (PAGE_SHIFT + page_order(buffer));
+}
+
+static int perf_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+        struct perf_event *event = vma->vm_file->private_data;
+        struct perf_buffer *buffer;
+        int ret = VM_FAULT_SIGBUS;
+
+        if (vmf->flags & FAULT_FLAG_MKWRITE) {
+                if (vmf->pgoff == 0)
+                        ret = 0;
+                return ret;
+        }
+
+        rcu_read_lock();
+        buffer = rcu_dereference(event->buffer);
+        if (!buffer)
+                goto unlock;
+
+        if (vmf->pgoff && (vmf->flags & FAULT_FLAG_WRITE))
+                goto unlock;
+
+        vmf->page = perf_mmap_to_page(buffer, vmf->pgoff);
+        if (!vmf->page)
+                goto unlock;
+
+        get_page(vmf->page);
+        vmf->page->mapping = vma->vm_file->f_mapping;
+        vmf->page->index   = vmf->pgoff;
+
+        ret = 0;
+unlock:
+        rcu_read_unlock();
+
+        return ret;
+}
+
+static void perf_buffer_free_rcu(struct rcu_head *rcu_head)
+{
+        struct perf_buffer *buffer;
+
+        buffer = container_of(rcu_head, struct perf_buffer, rcu_head);
+        perf_buffer_free(buffer);
+}
+
+static struct perf_buffer *perf_buffer_get(struct perf_event *event)
+{
+        struct perf_buffer *buffer;
+
+        rcu_read_lock();
+        buffer = rcu_dereference(event->buffer);
+        if (buffer) {
+                if (!atomic_inc_not_zero(&buffer->refcount))
+                        buffer = NULL;
+        }
+        rcu_read_unlock();
+
+        return buffer;
+}
+
+static void perf_buffer_put(struct perf_buffer *buffer)
+{
+        if (!atomic_dec_and_test(&buffer->refcount))
+                return;
+
+        call_rcu(&buffer->rcu_head, perf_buffer_free_rcu);
+}
+
+static void perf_mmap_open(struct vm_area_struct *vma)
+{
+        struct perf_event *event = vma->vm_file->private_data;
+
+        atomic_inc(&event->mmap_count);
+}
+
+static void perf_mmap_close(struct vm_area_struct *vma)
+{
+        struct perf_event *event = vma->vm_file->private_data;
+
+        if (atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex)) {
+                unsigned long size = perf_data_size(event->buffer);
+                struct user_struct *user = event->mmap_user;
+                struct perf_buffer *buffer = event->buffer;
+
+                atomic_long_sub((size >> PAGE_SHIFT) + 1, &user->locked_vm);
+                vma->vm_mm->locked_vm -= event->mmap_locked;
+                rcu_assign_pointer(event->buffer, NULL);
+                mutex_unlock(&event->mmap_mutex);
+
+                perf_buffer_put(buffer);
+                free_uid(user);
+        }
+}
+
+static const struct vm_operations_struct perf_mmap_vmops = {
+        .open           = perf_mmap_open,
+        .close          = perf_mmap_close,
+        .fault          = perf_mmap_fault,
+        .page_mkwrite   = perf_mmap_fault,
+};
+
+static int perf_mmap(struct file *file, struct vm_area_struct *vma)
+{
+        struct perf_event *event = file->private_data;
+        unsigned long user_locked, user_lock_limit;
+        struct user_struct *user = current_user();
+        unsigned long locked, lock_limit;
+        struct perf_buffer *buffer;
+        unsigned long vma_size;
+        unsigned long nr_pages;
+        long user_extra, extra;
+        int ret = 0, flags = 0;
+
+        /*
+         * Don't allow mmap() of inherited per-task counters. This would
+         * create a performance issue due to all children writing to the
+         * same buffer.
+         */
+        if (event->cpu == -1 && event->attr.inherit)
+                return -EINVAL;
+
+        if (!(vma->vm_flags & VM_SHARED))
+                return -EINVAL;
+
+        vma_size = vma->vm_end - vma->vm_start;
+        nr_pages = (vma_size / PAGE_SIZE) - 1;
+
+        /*
+         * If we have buffer pages ensure they're a power-of-two number, so we
+         * can do bitmasks instead of modulo.
+         */
+        if (nr_pages != 0 && !is_power_of_2(nr_pages))
+                return -EINVAL;
+
+        if (vma_size != PAGE_SIZE * (1 + nr_pages))
+                return -EINVAL;
+
+        if (vma->vm_pgoff != 0)
+                return -EINVAL;
+
+        WARN_ON_ONCE(event->ctx->parent_ctx);
+        mutex_lock(&event->mmap_mutex);
+        if (event->buffer) {
+                if (event->buffer->nr_pages == nr_pages)
+                        atomic_inc(&event->buffer->refcount);
+                else
+                        ret = -EINVAL;
+                goto unlock;
+        }
+
+        user_extra = nr_pages + 1;
+        user_lock_limit = sysctl_perf_event_mlock >> (PAGE_SHIFT - 10);
+
+        /*
+         * Increase the limit linearly with more CPUs:
+         */
+        user_lock_limit *= num_online_cpus();
+
+        user_locked = atomic_long_read(&user->locked_vm) + user_extra;
+
+        extra = 0;
+        if (user_locked > user_lock_limit)
+                extra = user_locked - user_lock_limit;
+
+        lock_limit = rlimit(RLIMIT_MEMLOCK);
+        lock_limit >>= PAGE_SHIFT;
+        locked = vma->vm_mm->locked_vm + extra;
+
+        if ((locked > lock_limit) && perf_paranoid_tracepoint_raw() &&
+                !capable(CAP_IPC_LOCK)) {
+                ret = -EPERM;
+                goto unlock;
+        }
+
+        WARN_ON(event->buffer);
+
+        if (vma->vm_flags & VM_WRITE)
+                flags |= PERF_BUFFER_WRITABLE;
+
+        buffer = perf_buffer_alloc(nr_pages, event->attr.wakeup_watermark,
+                                   event->cpu, flags);
+        if (!buffer) {
+                ret = -ENOMEM;
+                goto unlock;
+        }
+        rcu_assign_pointer(event->buffer, buffer);
+
+        atomic_long_add(user_extra, &user->locked_vm);
+        event->mmap_locked = extra;
+        event->mmap_user = get_current_user();
+        vma->vm_mm->locked_vm += event->mmap_locked;
+
+unlock:
+        if (!ret)
+                atomic_inc(&event->mmap_count);
+        mutex_unlock(&event->mmap_mutex);
+
+        vma->vm_flags |= VM_RESERVED;
+        vma->vm_ops = &perf_mmap_vmops;
+
+        return ret;
+}
+
+static int perf_fasync(int fd, struct file *filp, int on)
+{
+        struct inode *inode = filp->f_path.dentry->d_inode;
+        struct perf_event *event = filp->private_data;
+        int retval;
+
+        mutex_lock(&inode->i_mutex);
+        retval = fasync_helper(fd, filp, on, &event->fasync);
+        mutex_unlock(&inode->i_mutex);
+
+        if (retval < 0)
+                return retval;
+
+        return 0;
+}
+
+static const struct file_operations perf_fops = {
+        .llseek                 = no_llseek,
+        .release                = perf_release,
+        .read                   = perf_read,
+        .poll                   = perf_poll,
+        .unlocked_ioctl         = perf_ioctl,
+        .compat_ioctl           = perf_ioctl,
+        .mmap                   = perf_mmap,
+        .fasync                 = perf_fasync,
+};
+
+/*
+ * Perf event wakeup
+ *
+ * If there's data, ensure we set the poll() state and publish everything
+ * to user-space before waking everybody up.
+ */
+
+void perf_event_wakeup(struct perf_event *event)
+{
+        wake_up_all(&event->waitq);
+
+        if (event->pending_kill) {
+                kill_fasync(&event->fasync, SIGIO, event->pending_kill);
+                event->pending_kill = 0;
+        }
+}
+
+static void perf_pending_event(struct irq_work *entry)
+{
+        struct perf_event *event = container_of(entry,
+                        struct perf_event, pending);
+
+        if (event->pending_disable) {
+                event->pending_disable = 0;
+                __perf_event_disable(event);
+        }
+
+        if (event->pending_wakeup) {
+                event->pending_wakeup = 0;
+                perf_event_wakeup(event);
+        }
+}
+
+/*
+ * We assume there is only KVM supporting the callbacks.
+ * Later on, we might change it to a list if there is
+ * another virtualization implementation supporting the callbacks.
+ */
+struct perf_guest_info_callbacks *perf_guest_cbs;
+
+int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+{
+        perf_guest_cbs = cbs;
+        return 0;
+}
+EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
+
+int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+{
+        perf_guest_cbs = NULL;
+        return 0;
+}
+EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
+
+/*
+ * Output
+ */
+static bool perf_output_space(struct perf_buffer *buffer, unsigned long tail,
+                              unsigned long offset, unsigned long head)
+{
+        unsigned long mask;
+
+        if (!buffer->writable)
+                return true;
+
+        mask = perf_data_size(buffer) - 1;
+
+        offset = (offset - tail) & mask;
+        head   = (head   - tail) & mask;
+
+        if ((int)(head - offset) < 0)
+                return false;
+
+        return true;
+}
+
+static void perf_output_wakeup(struct perf_output_handle *handle)
+{
+        atomic_set(&handle->buffer->poll, POLL_IN);
+
+        if (handle->nmi) {
+                handle->event->pending_wakeup = 1;
+                irq_work_queue(&handle->event->pending);
+        } else
+                perf_event_wakeup(handle->event);
+}
+
+/*
+ * We need to ensure a later event_id doesn't publish a head when a former
+ * event isn't done writing. However since we need to deal with NMIs we
+ * cannot fully serialize things.
+ *
+ * We only publish the head (and generate a wakeup) when the outer-most
+ * event completes.
+ */
+static void perf_output_get_handle(struct perf_output_handle *handle)
+{
+        struct perf_buffer *buffer = handle->buffer;
+
+        preempt_disable();
+        local_inc(&buffer->nest);
+        handle->wakeup = local_read(&buffer->wakeup);
+}
+
+static void perf_output_put_handle(struct perf_output_handle *handle)
+{
+        struct perf_buffer *buffer = handle->buffer;
+        unsigned long head;
+
+again:
+        head = local_read(&buffer->head);
+
+        /*
+         * IRQ/NMI can happen here, which means we can miss a head update.
+         */
+
+        if (!local_dec_and_test(&buffer->nest))
+                goto out;
+
+        /*
+         * Publish the known good head. Rely on the full barrier implied
+         * by atomic_dec_and_test() order the buffer->head read and this
+         * write.
+         */
+        buffer->user_page->data_head = head;
+
+        /*
+         * Now check if we missed an update, rely on the (compiler)
+         * barrier in atomic_dec_and_test() to re-read buffer->head.
+         */
+        if (unlikely(head != local_read(&buffer->head))) {
+                local_inc(&buffer->nest);
+                goto again;
+        }
+
+        if (handle->wakeup != local_read(&buffer->wakeup))
+                perf_output_wakeup(handle);
+
+out:
+        preempt_enable();
+}
+
+__always_inline void perf_output_copy(struct perf_output_handle *handle,
+                      const void *buf, unsigned int len)
+{
+        do {
+                unsigned long size = min_t(unsigned long, handle->size, len);
+
+                memcpy(handle->addr, buf, size);
+
+                len -= size;
+                handle->addr += size;
+                buf += size;
+                handle->size -= size;
+                if (!handle->size) {
+                        struct perf_buffer *buffer = handle->buffer;
+
+                        handle->page++;
+                        handle->page &= buffer->nr_pages - 1;
+                        handle->addr = buffer->data_pages[handle->page];
+                        handle->size = PAGE_SIZE << page_order(buffer);
+                }
+        } while (len);
+}
+
+static void __perf_event_header__init_id(struct perf_event_header *header,
+                                         struct perf_sample_data *data,
+                                         struct perf_event *event)
+{
+        u64 sample_type = event->attr.sample_type;
+
+        data->type = sample_type;
+        header->size += event->id_header_size;
+
+        if (sample_type & PERF_SAMPLE_TID) {
+                /* namespace issues */
+                data->tid_entry.pid = perf_event_pid(event, current);
+                data->tid_entry.tid = perf_event_tid(event, current);
+        }
+
+        if (sample_type & PERF_SAMPLE_TIME)
+                data->time = perf_clock();
+
+        if (sample_type & PERF_SAMPLE_ID)
+                data->id = primary_event_id(event);
+
+        if (sample_type & PERF_SAMPLE_STREAM_ID)
+                data->stream_id = event->id;
+
+        if (sample_type & PERF_SAMPLE_CPU) {
+                data->cpu_entry.cpu      = raw_smp_processor_id();
+                data->cpu_entry.reserved = 0;
+        }
+}
+
+static void perf_event_header__init_id(struct perf_event_header *header,
+                                       struct perf_sample_data *data,
+                                       struct perf_event *event)
+{
+        if (event->attr.sample_id_all)
+                __perf_event_header__init_id(header, data, event);
+}
+
+static void __perf_event__output_id_sample(struct perf_output_handle *handle,
+                                           struct perf_sample_data *data)
+{
+        u64 sample_type = data->type;
+
+        if (sample_type & PERF_SAMPLE_TID)
+                perf_output_put(handle, data->tid_entry);
+
+        if (sample_type & PERF_SAMPLE_TIME)
+                perf_output_put(handle, data->time);
+
+        if (sample_type & PERF_SAMPLE_ID)
+                perf_output_put(handle, data->id);
+
+        if (sample_type & PERF_SAMPLE_STREAM_ID)
+                perf_output_put(handle, data->stream_id);
+
+        if (sample_type & PERF_SAMPLE_CPU)
+                perf_output_put(handle, data->cpu_entry);
+}
+
+static void perf_event__output_id_sample(struct perf_event *event,
+                                         struct perf_output_handle *handle,
+                                         struct perf_sample_data *sample)
+{
+        if (event->attr.sample_id_all)
+                __perf_event__output_id_sample(handle, sample);
+}
+
+int perf_output_begin(struct perf_output_handle *handle,
+                      struct perf_event *event, unsigned int size,
+                      int nmi, int sample)
+{
+        struct perf_buffer *buffer;
+        unsigned long tail, offset, head;
+        int have_lost;
+        struct perf_sample_data sample_data;
+        struct {
+                struct perf_event_header header;
+                u64                      id;
+                u64                      lost;
+        } lost_event;
+
+        rcu_read_lock();
+        /*
+         * For inherited events we send all the output towards the parent.
+         */
+        if (event->parent)
+                event = event->parent;
+
+        buffer = rcu_dereference(event->buffer);
+        if (!buffer)
+                goto out;
+
+        handle->buffer  = buffer;
+        handle->event   = event;
+        handle->nmi     = nmi;
+        handle->sample  = sample;
+
+        if (!buffer->nr_pages)
+                goto out;
+
+        have_lost = local_read(&buffer->lost);
+        if (have_lost) {
+                lost_event.header.size = sizeof(lost_event);
+                perf_event_header__init_id(&lost_event.header, &sample_data,
+                                           event);
+                size += lost_event.header.size;
+        }
+
+        perf_output_get_handle(handle);
+
+        do {
+                /*
+                 * Userspace could choose to issue a mb() before updating the
+                 * tail pointer. So that all reads will be completed before the
+                 * write is issued.
+                 */
+                tail = ACCESS_ONCE(buffer->user_page->data_tail);
+                smp_rmb();
+                offset = head = local_read(&buffer->head);
+                head += size;
+                if (unlikely(!perf_output_space(buffer, tail, offset, head)))
+                        goto fail;
+        } while (local_cmpxchg(&buffer->head, offset, head) != offset);
+
+        if (head - local_read(&buffer->wakeup) > buffer->watermark)
+                local_add(buffer->watermark, &buffer->wakeup);
+
+        handle->page = offset >> (PAGE_SHIFT + page_order(buffer));
+        handle->page &= buffer->nr_pages - 1;
+        handle->size = offset & ((PAGE_SIZE << page_order(buffer)) - 1);
+        handle->addr = buffer->data_pages[handle->page];
+        handle->addr += handle->size;
+        handle->size = (PAGE_SIZE << page_order(buffer)) - handle->size;
+
+        if (have_lost) {
+                lost_event.header.type = PERF_RECORD_LOST;
+                lost_event.header.misc = 0;
+                lost_event.id          = event->id;
+                lost_event.lost        = local_xchg(&buffer->lost, 0);
+
+                perf_output_put(handle, lost_event);
+                perf_event__output_id_sample(event, handle, &sample_data);
+        }
+
+        return 0;
+
+fail:
+        local_inc(&buffer->lost);
+        perf_output_put_handle(handle);
+out:
+        rcu_read_unlock();
+
+        return -ENOSPC;
+}
+
+void perf_output_end(struct perf_output_handle *handle)
+{
+        struct perf_event *event = handle->event;
+        struct perf_buffer *buffer = handle->buffer;
+
+        int wakeup_events = event->attr.wakeup_events;
+
+        if (handle->sample && wakeup_events) {
+                int events = local_inc_return(&buffer->events);
+                if (events >= wakeup_events) {
+                        local_sub(wakeup_events, &buffer->events);
+                        local_inc(&buffer->wakeup);
+                }
+        }
+
+        perf_output_put_handle(handle);
+        rcu_read_unlock();
+}
+
+static void perf_output_read_one(struct perf_output_handle *handle,
+                                 struct perf_event *event,
+                                 u64 enabled, u64 running)
+{
+        u64 read_format = event->attr.read_format;
+        u64 values[4];
+        int n = 0;
+
+        values[n++] = perf_event_count(event);
+        if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
+                values[n++] = enabled +
+                        atomic64_read(&event->child_total_time_enabled);
+        }
+        if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
+                values[n++] = running +
+                        atomic64_read(&event->child_total_time_running);
+        }
+        if (read_format & PERF_FORMAT_ID)
+                values[n++] = primary_event_id(event);
+
+        perf_output_copy(handle, values, n * sizeof(u64));
+}
+
+/*
+ * XXX PERF_FORMAT_GROUP vs inherited events seems difficult.
+ */
+static void perf_output_read_group(struct perf_output_handle *handle,
+                            struct perf_event *event,
+                            u64 enabled, u64 running)
+{
+        struct perf_event *leader = event->group_leader, *sub;
+        u64 read_format = event->attr.read_format;
+        u64 values[5];
+        int n = 0;
+
+        values[n++] = 1 + leader->nr_siblings;
+
+        if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+                values[n++] = enabled;
+
+        if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+                values[n++] = running;
+
+        if (leader != event)
+                leader->pmu->read(leader);
+
+        values[n++] = perf_event_count(leader);
+        if (read_format & PERF_FORMAT_ID)
+                values[n++] = primary_event_id(leader);
+
+        perf_output_copy(handle, values, n * sizeof(u64));
+
+        list_for_each_entry(sub, &leader->sibling_list, group_entry) {
+                n = 0;
+
+                if (sub != event)
+                        sub->pmu->read(sub);
+
+                values[n++] = perf_event_count(sub);
+                if (read_format & PERF_FORMAT_ID)
+                        values[n++] = primary_event_id(sub);
+
+                perf_output_copy(handle, values, n * sizeof(u64));
+        }
+}
+
+#define PERF_FORMAT_TOTAL_TIMES (PERF_FORMAT_TOTAL_TIME_ENABLED|\
+                                 PERF_FORMAT_TOTAL_TIME_RUNNING)
+
+static void perf_output_read(struct perf_output_handle *handle,
+                             struct perf_event *event)
+{
+        u64 enabled = 0, running = 0, now, ctx_time;
+        u64 read_format = event->attr.read_format;
+
+        /*
+         * compute total_time_enabled, total_time_running
+         * based on snapshot values taken when the event
+         * was last scheduled in.
+         *
+         * we cannot simply called update_context_time()
+         * because of locking issue as we are called in
+         * NMI context
+         */
+        if (read_format & PERF_FORMAT_TOTAL_TIMES) {
+                now = perf_clock();
+                ctx_time = event->shadow_ctx_time + now;
+                enabled = ctx_time - event->tstamp_enabled;
+                running = ctx_time - event->tstamp_running;
+        }
+
+        if (event->attr.read_format & PERF_FORMAT_GROUP)
+                perf_output_read_group(handle, event, enabled, running);
+        else
+                perf_output_read_one(handle, event, enabled, running);
+}
+
+void perf_output_sample(struct perf_output_handle *handle,
+                        struct perf_event_header *header,
+                        struct perf_sample_data *data,
+                        struct perf_event *event)
+{
+        u64 sample_type = data->type;
+
+        perf_output_put(handle, *header);
+
+        if (sample_type & PERF_SAMPLE_IP)
+                perf_output_put(handle, data->ip);
+
+        if (sample_type & PERF_SAMPLE_TID)
+                perf_output_put(handle, data->tid_entry);
+
+        if (sample_type & PERF_SAMPLE_TIME)
+                perf_output_put(handle, data->time);
+
+        if (sample_type & PERF_SAMPLE_ADDR)
+                perf_output_put(handle, data->addr);
+
+        if (sample_type & PERF_SAMPLE_ID)
+                perf_output_put(handle, data->id);
+
+        if (sample_type & PERF_SAMPLE_STREAM_ID)
+                perf_output_put(handle, data->stream_id);
+
+        if (sample_type & PERF_SAMPLE_CPU)
+                perf_output_put(handle, data->cpu_entry);
+
+        if (sample_type & PERF_SAMPLE_PERIOD)
+                perf_output_put(handle, data->period);
+
+        if (sample_type & PERF_SAMPLE_READ)
+                perf_output_read(handle, event);
+
+        if (sample_type & PERF_SAMPLE_CALLCHAIN) {
+                if (data->callchain) {
+                        int size = 1;
+
+                        if (data->callchain)
+                                size += data->callchain->nr;
+
+                        size *= sizeof(u64);
+
+                        perf_output_copy(handle, data->callchain, size);
+                } else {
+                        u64 nr = 0;
+                        perf_output_put(handle, nr);
+                }
+        }
+
+        if (sample_type & PERF_SAMPLE_RAW) {
+                if (data->raw) {
+                        perf_output_put(handle, data->raw->size);
+                        perf_output_copy(handle, data->raw->data,
+                                         data->raw->size);
+                } else {
+                        struct {
+                                u32     size;
+                                u32     data;
+                        } raw = {
+                                .size = sizeof(u32),
+                                .data = 0,
+                        };
+                        perf_output_put(handle, raw);
+                }
+        }
+}
+
+void perf_prepare_sample(struct perf_event_header *header,
+                         struct perf_sample_data *data,
+                         struct perf_event *event,
+                         struct pt_regs *regs)
+{
+        u64 sample_type = event->attr.sample_type;
+
+        header->type = PERF_RECORD_SAMPLE;
+        header->size = sizeof(*header) + event->header_size;
+
+        header->misc = 0;
+        header->misc |= perf_misc_flags(regs);
+
+        __perf_event_header__init_id(header, data, event);
+
+        if (sample_type & PERF_SAMPLE_IP)
+                data->ip = perf_instruction_pointer(regs);
+
+        if (sample_type & PERF_SAMPLE_CALLCHAIN) {
+                int size = 1;
+
+                data->callchain = perf_callchain(regs);
+
+                if (data->callchain)
+                        size += data->callchain->nr;
+
+                header->size += size * sizeof(u64);
+        }
+
+        if (sample_type & PERF_SAMPLE_RAW) {
+                int size = sizeof(u32);
+
+                if (data->raw)
+                        size += data->raw->size;
+                else
+                        size += sizeof(u32);
+
+                WARN_ON_ONCE(size & (sizeof(u64)-1));
+                header->size += size;
+        }
+}
+
+static void perf_event_output(struct perf_event *event, int nmi,
+                                struct perf_sample_data *data,
+                                struct pt_regs *regs)
+{
+        struct perf_output_handle handle;
+        struct perf_event_header header;
+
+        /* protect the callchain buffers */
+        rcu_read_lock();
+
+        perf_prepare_sample(&header, data, event, regs);
+
+        if (perf_output_begin(&handle, event, header.size, nmi, 1))
+                goto exit;
+
+        perf_output_sample(&handle, &header, data, event);
+
+        perf_output_end(&handle);
+
+exit:
+        rcu_read_unlock();
+}
+
+/*
+ * read event_id
+ */
+
+struct perf_read_event {
+        struct perf_event_header        header;
+
+        u32                             pid;
+        u32                             tid;
+};
+
+static void
+perf_event_read_event(struct perf_event *event,
+                        struct task_struct *task)
+{
+        struct perf_output_handle handle;
+        struct perf_sample_data sample;
+        struct perf_read_event read_event = {
+                .header = {
+                        .type = PERF_RECORD_READ,
+                        .misc = 0,
+                        .size = sizeof(read_event) + event->read_size,
+                },
+                .pid = perf_event_pid(event, task),
+                .tid = perf_event_tid(event, task),
+        };
+        int ret;
+
+        perf_event_header__init_id(&read_event.header, &sample, event);
+        ret = perf_output_begin(&handle, event, read_event.header.size, 0, 0);
+        if (ret)
+                return;
+
+        perf_output_put(&handle, read_event);
+        perf_output_read(&handle, event);
+        perf_event__output_id_sample(event, &handle, &sample);
+
+        perf_output_end(&handle);
+}
+
+/*
+ * task tracking -- fork/exit
+ *
+ * enabled by: attr.comm | attr.mmap | attr.mmap_data | attr.task
+ */
+
+struct perf_task_event {
+        struct task_struct              *task;
+        struct perf_event_context       *task_ctx;
+
+        struct {
+                struct perf_event_header        header;
+
+                u32                             pid;
+                u32                             ppid;
+                u32                             tid;
+                u32                             ptid;
+                u64                             time;
+        } event_id;
+};
+
+static void perf_event_task_output(struct perf_event *event,
+                                     struct perf_task_event *task_event)
+{
+        struct perf_output_handle handle;
+        struct perf_sample_data sample;
+        struct task_struct *task = task_event->task;
+        int ret, size = task_event->event_id.header.size;
+
+        perf_event_header__init_id(&task_event->event_id.header, &sample, event);
+
+        ret = perf_output_begin(&handle, event,
+                                task_event->event_id.header.size, 0, 0);
+        if (ret)
+                goto out;
+
+        task_event->event_id.pid = perf_event_pid(event, task);
+        task_event->event_id.ppid = perf_event_pid(event, current);
+
+        task_event->event_id.tid = perf_event_tid(event, task);
+        task_event->event_id.ptid = perf_event_tid(event, current);
+
+        perf_output_put(&handle, task_event->event_id);
+
+        perf_event__output_id_sample(event, &handle, &sample);
+
+        perf_output_end(&handle);
+out:
+        task_event->event_id.header.size = size;
+}
+
+static int perf_event_task_match(struct perf_event *event)
+{
+        if (event->state < PERF_EVENT_STATE_INACTIVE)
+                return 0;
+
+        if (!event_filter_match(event))
+                return 0;
+
+        if (event->attr.comm || event->attr.mmap ||
+            event->attr.mmap_data || event->attr.task)
+                return 1;
+
+        return 0;
+}
+
+static void perf_event_task_ctx(struct perf_event_context *ctx,
+                                  struct perf_task_event *task_event)
+{
+        struct perf_event *event;
+
+        list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
+                if (perf_event_task_match(event))
+                        perf_event_task_output(event, task_event);
+        }
+}
+
+static void perf_event_task_event(struct perf_task_event *task_event)
+{
+        struct perf_cpu_context *cpuctx;
+        struct perf_event_context *ctx;
+        struct pmu *pmu;
+        int ctxn;
+
+        rcu_read_lock();
+        list_for_each_entry_rcu(pmu, &pmus, entry) {
+                cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
+                if (cpuctx->active_pmu != pmu)
+                        goto next;
+                perf_event_task_ctx(&cpuctx->ctx, task_event);
+
+                ctx = task_event->task_ctx;
+                if (!ctx) {
+                        ctxn = pmu->task_ctx_nr;
+                        if (ctxn < 0)
+                                goto next;
+                        ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
+                }
+                if (ctx)
+                        perf_event_task_ctx(ctx, task_event);
+next:
+                put_cpu_ptr(pmu->pmu_cpu_context);
+        }
+        rcu_read_unlock();
+}
+
+static void perf_event_task(struct task_struct *task,
+                              struct perf_event_context *task_ctx,
+                              int new)
+{
+        struct perf_task_event task_event;
+
+        if (!atomic_read(&nr_comm_events) &&
+            !atomic_read(&nr_mmap_events) &&
+            !atomic_read(&nr_task_events))
+                return;
+
+        task_event = (struct perf_task_event){
+                .task     = task,
+                .task_ctx = task_ctx,
+                .event_id    = {
+                        .header = {
+                                .type = new ? PERF_RECORD_FORK : PERF_RECORD_EXIT,
+                                .misc = 0,
+                                .size = sizeof(task_event.event_id),
+                        },
+                        /* .pid  */
+                        /* .ppid */
+                        /* .tid  */
+                        /* .ptid */
+                        .time = perf_clock(),
+                },
+        };
+
+        perf_event_task_event(&task_event);
+}
+
+void perf_event_fork(struct task_struct *task)
+{
+        perf_event_task(task, NULL, 1);
+}
+
+/*
+ * comm tracking
+ */
+
+struct perf_comm_event {
+        struct task_struct      *task;
+        char                    *comm;
+        int                     comm_size;
+
+        struct {
+                struct perf_event_header        header;
+
+                u32                             pid;
+                u32                             tid;
+        } event_id;
+};
+
+static void perf_event_comm_output(struct perf_event *event,
+                                     struct perf_comm_event *comm_event)
+{
+        struct perf_output_handle handle;
+        struct perf_sample_data sample;
+        int size = comm_event->event_id.header.size;
+        int ret;
+
+        perf_event_header__init_id(&comm_event->event_id.header, &sample, event);
+        ret = perf_output_begin(&handle, event,
+                                comm_event->event_id.header.size, 0, 0);
+
+        if (ret)
+                goto out;
+
+        comm_event->event_id.pid = perf_event_pid(event, comm_event->task);
+        comm_event->event_id.tid = perf_event_tid(event, comm_event->task);
+
+        perf_output_put(&handle, comm_event->event_id);
+        perf_output_copy(&handle, comm_event->comm,
+                                   comm_event->comm_size);
+
+        perf_event__output_id_sample(event, &handle, &sample);
+
+        perf_output_end(&handle);
+out:
+        comm_event->event_id.header.size = size;
+}
+
+static int perf_event_comm_match(struct perf_event *event)
+{
+        if (event->state < PERF_EVENT_STATE_INACTIVE)
+                return 0;
+
+        if (!event_filter_match(event))
+                return 0;
+
+        if (event->attr.comm)
+                return 1;
+
+        return 0;
+}
+
+static void perf_event_comm_ctx(struct perf_event_context *ctx,
+                                  struct perf_comm_event *comm_event)
+{
+        struct perf_event *event;
+
+        list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
+                if (perf_event_comm_match(event))
+                        perf_event_comm_output(event, comm_event);
+        }
+}
+
+static void perf_event_comm_event(struct perf_comm_event *comm_event)
+{
+        struct perf_cpu_context *cpuctx;
+        struct perf_event_context *ctx;
+        char comm[TASK_COMM_LEN];
+        unsigned int size;
+        struct pmu *pmu;
+        int ctxn;
+
+        memset(comm, 0, sizeof(comm));
+        strlcpy(comm, comm_event->task->comm, sizeof(comm));
+        size = ALIGN(strlen(comm)+1, sizeof(u64));
+
+        comm_event->comm = comm;
+        comm_event->comm_size = size;
+
+        comm_event->event_id.header.size = sizeof(comm_event->event_id) + size;
+        rcu_read_lock();
+        list_for_each_entry_rcu(pmu, &pmus, entry) {
+                cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
+                if (cpuctx->active_pmu != pmu)
+                        goto next;
+                perf_event_comm_ctx(&cpuctx->ctx, comm_event);
+
+                ctxn = pmu->task_ctx_nr;
+                if (ctxn < 0)
+                        goto next;
+
+                ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
+                if (ctx)
+                        perf_event_comm_ctx(ctx, comm_event);
+next:
+                put_cpu_ptr(pmu->pmu_cpu_context);
+        }
+        rcu_read_unlock();
+}
+
+void perf_event_comm(struct task_struct *task)
+{
+        struct perf_comm_event comm_event;
+        struct perf_event_context *ctx;
+        int ctxn;
+
+        for_each_task_context_nr(ctxn) {
+                ctx = task->perf_event_ctxp[ctxn];
+                if (!ctx)
+                        continue;
+
+                perf_event_enable_on_exec(ctx);
+        }
+
+        if (!atomic_read(&nr_comm_events))
+                return;
+
+        comm_event = (struct perf_comm_event){
+                .task   = task,
+                /* .comm      */
+                /* .comm_size */
+                .event_id  = {
+                        .header = {
+                                .type = PERF_RECORD_COMM,
+                                .misc = 0,
+                                /* .size */
+                        },
+                        /* .pid */
+                        /* .tid */
+                },
+        };
+
+        perf_event_comm_event(&comm_event);
+}
+
+/*
+ * mmap tracking
+ */
+
+struct perf_mmap_event {
+        struct vm_area_struct   *vma;
+
+        const char              *file_name;
+        int                     file_size;
+
+        struct {
+                struct perf_event_header        header;
+
+                u32                             pid;
+                u32                             tid;
+                u64                             start;
+                u64                             len;
+                u64                             pgoff;
+        } event_id;
+};
+
+static void perf_event_mmap_output(struct perf_event *event,
+                                     struct perf_mmap_event *mmap_event)
+{
+        struct perf_output_handle handle;
+        struct perf_sample_data sample;
+        int size = mmap_event->event_id.header.size;
+        int ret;
+
+        perf_event_header__init_id(&mmap_event->event_id.header, &sample, event);
+        ret = perf_output_begin(&handle, event,
+                                mmap_event->event_id.header.size, 0, 0);
+        if (ret)
+                goto out;
+
+        mmap_event->event_id.pid = perf_event_pid(event, current);
+        mmap_event->event_id.tid = perf_event_tid(event, current);
+
+        perf_output_put(&handle, mmap_event->event_id);
+        perf_output_copy(&handle, mmap_event->file_name,
+                                   mmap_event->file_size);
+
+        perf_event__output_id_sample(event, &handle, &sample);
+
+        perf_output_end(&handle);
+out:
+        mmap_event->event_id.header.size = size;
+}
+
+static int perf_event_mmap_match(struct perf_event *event,
+                                   struct perf_mmap_event *mmap_event,
+                                   int executable)
+{
+        if (event->state < PERF_EVENT_STATE_INACTIVE)
+                return 0;
+
+        if (!event_filter_match(event))
+                return 0;
+
+        if ((!executable && event->attr.mmap_data) ||
+            (executable && event->attr.mmap))
+                return 1;
+
+        return 0;
+}
+
+static void perf_event_mmap_ctx(struct perf_event_context *ctx,
+                                  struct perf_mmap_event *mmap_event,
+                                  int executable)
+{
+        struct perf_event *event;
+
+        list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
+                if (perf_event_mmap_match(event, mmap_event, executable))
+                        perf_event_mmap_output(event, mmap_event);
+        }
+}
+
+static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
+{
+        struct perf_cpu_context *cpuctx;
+        struct perf_event_context *ctx;
+        struct vm_area_struct *vma = mmap_event->vma;
+        struct file *file = vma->vm_file;
+        unsigned int size;
+        char tmp[16];
+        char *buf = NULL;
+        const char *name;
+        struct pmu *pmu;
+        int ctxn;
+
+        memset(tmp, 0, sizeof(tmp));
+
+        if (file) {
+                /*
+                 * d_path works from the end of the buffer backwards, so we
+                 * need to add enough zero bytes after the string to handle
+                 * the 64bit alignment we do later.
+                 */
+                buf = kzalloc(PATH_MAX + sizeof(u64), GFP_KERNEL);
+                if (!buf) {
+                        name = strncpy(tmp, "//enomem", sizeof(tmp));
+                        goto got_name;
+                }
+                name = d_path(&file->f_path, buf, PATH_MAX);
+                if (IS_ERR(name)) {
+                        name = strncpy(tmp, "//toolong", sizeof(tmp));
+                        goto got_name;
+                }
+        } else {
+                if (arch_vma_name(mmap_event->vma)) {
+                        name = strncpy(tmp, arch_vma_name(mmap_event->vma),
+                                       sizeof(tmp));
+                        goto got_name;
+                }
+
+                if (!vma->vm_mm) {
+                        name = strncpy(tmp, "[vdso]", sizeof(tmp));
+                        goto got_name;
+                } else if (vma->vm_start <= vma->vm_mm->start_brk &&
+                                vma->vm_end >= vma->vm_mm->brk) {
+                        name = strncpy(tmp, "[heap]", sizeof(tmp));
+                        goto got_name;
+                } else if (vma->vm_start <= vma->vm_mm->start_stack &&
+                                vma->vm_end >= vma->vm_mm->start_stack) {
+                        name = strncpy(tmp, "[stack]", sizeof(tmp));
+                        goto got_name;
+                }
+
+                name = strncpy(tmp, "//anon", sizeof(tmp));
+                goto got_name;
+        }
+
+got_name:
+        size = ALIGN(strlen(name)+1, sizeof(u64));
+
+        mmap_event->file_name = name;
+        mmap_event->file_size = size;
+
+        mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size;
+
+        rcu_read_lock();
+        list_for_each_entry_rcu(pmu, &pmus, entry) {
+                cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
+                if (cpuctx->active_pmu != pmu)
+                        goto next;
+                perf_event_mmap_ctx(&cpuctx->ctx, mmap_event,
+                                        vma->vm_flags & VM_EXEC);
+
+                ctxn = pmu->task_ctx_nr;
+                if (ctxn < 0)
+                        goto next;
+
+                ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
+                if (ctx) {
+                        perf_event_mmap_ctx(ctx, mmap_event,
+                                        vma->vm_flags & VM_EXEC);
+                }
+next:
+                put_cpu_ptr(pmu->pmu_cpu_context);
+        }
+        rcu_read_unlock();
+
+        kfree(buf);
+}
+
+void perf_event_mmap(struct vm_area_struct *vma)
+{
+        struct perf_mmap_event mmap_event;
+
+        if (!atomic_read(&nr_mmap_events))
+                return;
+
+        mmap_event = (struct perf_mmap_event){
+                .vma    = vma,
+                /* .file_name */
+                /* .file_size */
+                .event_id  = {
+                        .header = {
+                                .type = PERF_RECORD_MMAP,
+                                .misc = PERF_RECORD_MISC_USER,
+                                /* .size */
+                        },
+                        /* .pid */
+                        /* .tid */
+                        .start  = vma->vm_start,
+                        .len    = vma->vm_end - vma->vm_start,
+                        .pgoff  = (u64)vma->vm_pgoff << PAGE_SHIFT,
+                },
+        };
+
+        perf_event_mmap_event(&mmap_event);
+}
+
+/*
+ * IRQ throttle logging
+ */
+
+static void perf_log_throttle(struct perf_event *event, int enable)
+{
+        struct perf_output_handle handle;
+        struct perf_sample_data sample;
+        int ret;
+
+        struct {
+                struct perf_event_header        header;
+                u64                             time;
+                u64                             id;
+                u64                             stream_id;
+        } throttle_event = {
+                .header = {
+                        .type = PERF_RECORD_THROTTLE,
+                        .misc = 0,
+                        .size = sizeof(throttle_event),
+                },
+                .time           = perf_clock(),
+                .id             = primary_event_id(event),
+                .stream_id      = event->id,
+        };
+
+        if (enable)
+                throttle_event.header.type = PERF_RECORD_UNTHROTTLE;
+
+        perf_event_header__init_id(&throttle_event.header, &sample, event);
+
+        ret = perf_output_begin(&handle, event,
+                                throttle_event.header.size, 1, 0);
+        if (ret)
+                return;
+
+        perf_output_put(&handle, throttle_event);
+        perf_event__output_id_sample(event, &handle, &sample);
+        perf_output_end(&handle);
+}
+
+/*
+ * Generic event overflow handling, sampling.
+ */
+
+static int __perf_event_overflow(struct perf_event *event, int nmi,
+                                   int throttle, struct perf_sample_data *data,
+                                   struct pt_regs *regs)
+{
+        int events = atomic_read(&event->event_limit);
+        struct hw_perf_event *hwc = &event->hw;
+        int ret = 0;
+
+        /*
+         * Non-sampling counters might still use the PMI to fold short
+         * hardware counters, ignore those.
+         */
+        if (unlikely(!is_sampling_event(event)))
+                return 0;
+
+        if (unlikely(hwc->interrupts >= max_samples_per_tick)) {
+                if (throttle) {
+                        hwc->interrupts = MAX_INTERRUPTS;
+                        perf_log_throttle(event, 0);
+                        ret = 1;
+                }
+        } else
+                hwc->interrupts++;
+
+        if (event->attr.freq) {
+                u64 now = perf_clock();
+                s64 delta = now - hwc->freq_time_stamp;
+
+                hwc->freq_time_stamp = now;
+
+                if (delta > 0 && delta < 2*TICK_NSEC)
+                        perf_adjust_period(event, delta, hwc->last_period);
+        }
+
+        /*
+         * XXX event_limit might not quite work as expected on inherited
+         * events
+         */
+
+        event->pending_kill = POLL_IN;
+        if (events && atomic_dec_and_test(&event->event_limit)) {
+                ret = 1;
+                event->pending_kill = POLL_HUP;
+                if (nmi) {
+                        event->pending_disable = 1;
+                        irq_work_queue(&event->pending);
+                } else
+                        perf_event_disable(event);
+        }
+
+        if (event->overflow_handler)
+                event->overflow_handler(event, nmi, data, regs);
+        else
+                perf_event_output(event, nmi, data, regs);
+
+        return ret;
+}
+
+int perf_event_overflow(struct perf_event *event, int nmi,
+                          struct perf_sample_data *data,
+                          struct pt_regs *regs)
+{
+        return __perf_event_overflow(event, nmi, 1, data, regs);
+}
+
+/*
+ * Generic software event infrastructure
+ */
+
+struct swevent_htable {
+        struct swevent_hlist            *swevent_hlist;
+        struct mutex                    hlist_mutex;
+        int                             hlist_refcount;
+
+        /* Recursion avoidance in each contexts */
+        int                             recursion[PERF_NR_CONTEXTS];
+};
+
+static DEFINE_PER_CPU(struct swevent_htable, swevent_htable);
+
+/*
+ * We directly increment event->count and keep a second value in
+ * event->hw.period_left to count intervals. This period event
+ * is kept in the range [-sample_period, 0] so that we can use the
+ * sign as trigger.
+ */
+
+static u64 perf_swevent_set_period(struct perf_event *event)
+{
+        struct hw_perf_event *hwc = &event->hw;
+        u64 period = hwc->last_period;
+        u64 nr, offset;
+        s64 old, val;
+
+        hwc->last_period = hwc->sample_period;
+
+again:
+        old = val = local64_read(&hwc->period_left);
+        if (val < 0)
+                return 0;
+
+        nr = div64_u64(period + val, period);
+        offset = nr * period;
+        val -= offset;
+        if (local64_cmpxchg(&hwc->period_left, old, val) != old)
+                goto again;
+
+        return nr;
+}
+
+static void perf_swevent_overflow(struct perf_event *event, u64 overflow,
+                                    int nmi, struct perf_sample_data *data,
+                                    struct pt_regs *regs)
+{
+        struct hw_perf_event *hwc = &event->hw;
+        int throttle = 0;
+
+        data->period = event->hw.last_period;
+        if (!overflow)
+                overflow = perf_swevent_set_period(event);
+
+        if (hwc->interrupts == MAX_INTERRUPTS)
+                return;
+
+        for (; overflow; overflow--) {
+                if (__perf_event_overflow(event, nmi, throttle,
+                                            data, regs)) {
+                        /*
+                         * We inhibit the overflow from happening when
+                         * hwc->interrupts == MAX_INTERRUPTS.
+                         */
+                        break;
+                }
+                throttle = 1;
+        }
+}
+
+static void perf_swevent_event(struct perf_event *event, u64 nr,
+                               int nmi, struct perf_sample_data *data,
+                               struct pt_regs *regs)
+{
+        struct hw_perf_event *hwc = &event->hw;
+
+        local64_add(nr, &event->count);
+
+        if (!regs)
+                return;
+
+        if (!is_sampling_event(event))
+                return;
+
+        if (nr == 1 && hwc->sample_period == 1 && !event->attr.freq)
+                return perf_swevent_overflow(event, 1, nmi, data, regs);
+
+        if (local64_add_negative(nr, &hwc->period_left))
+                return;
+
+        perf_swevent_overflow(event, 0, nmi, data, regs);
+}
+
+static int perf_exclude_event(struct perf_event *event,
+                              struct pt_regs *regs)
+{
+        if (event->hw.state & PERF_HES_STOPPED)
+                return 1;
+
+        if (regs) {
+                if (event->attr.exclude_user && user_mode(regs))
+                        return 1;
+
+                if (event->attr.exclude_kernel && !user_mode(regs))
+                        return 1;
+        }
+
+        return 0;
+}
+
+static int perf_swevent_match(struct perf_event *event,
+                                enum perf_type_id type,
+                                u32 event_id,
+                                struct perf_sample_data *data,
+                                struct pt_regs *regs)
+{
+        if (event->attr.type != type)
+                return 0;
+
+        if (event->attr.config != event_id)
+                return 0;
+
+        if (perf_exclude_event(event, regs))
+                return 0;
+
+        return 1;
+}
+
+static inline u64 swevent_hash(u64 type, u32 event_id)
+{
+        u64 val = event_id | (type << 32);
+
+        return hash_64(val, SWEVENT_HLIST_BITS);
+}
+
+static inline struct hlist_head *
+__find_swevent_head(struct swevent_hlist *hlist, u64 type, u32 event_id)
+{
+        u64 hash = swevent_hash(type, event_id);
+
+        return &hlist->heads[hash];
+}
+
+/* For the read side: events when they trigger */
+static inline struct hlist_head *
+find_swevent_head_rcu(struct swevent_htable *swhash, u64 type, u32 event_id)
+{
+        struct swevent_hlist *hlist;
+
+        hlist = rcu_dereference(swhash->swevent_hlist);
+        if (!hlist)
+                return NULL;
+
+        return __find_swevent_head(hlist, type, event_id);
+}
+
+/* For the event head insertion and removal in the hlist */
+static inline struct hlist_head *
+find_swevent_head(struct swevent_htable *swhash, struct perf_event *event)
+{
+        struct swevent_hlist *hlist;
+        u32 event_id = event->attr.config;
+        u64 type = event->attr.type;
+
+        /*
+         * Event scheduling is always serialized against hlist allocation
+         * and release. Which makes the protected version suitable here.
+         * The context lock guarantees that.
+         */
+        hlist = rcu_dereference_protected(swhash->swevent_hlist,
+                                          lockdep_is_held(&event->ctx->lock));
+        if (!hlist)
+                return NULL;
+
+        return __find_swevent_head(hlist, type, event_id);
+}
+
+static void do_perf_sw_event(enum perf_type_id type, u32 event_id,
+                                    u64 nr, int nmi,
+                                    struct perf_sample_data *data,
+                                    struct pt_regs *regs)
+{
+        struct swevent_htable *swhash = &__get_cpu_var(swevent_htable);
+        struct perf_event *event;
+        struct hlist_node *node;
+        struct hlist_head *head;
+
+        rcu_read_lock();
+        head = find_swevent_head_rcu(swhash, type, event_id);
+        if (!head)
+                goto end;
+
+        hlist_for_each_entry_rcu(event, node, head, hlist_entry) {
+                if (perf_swevent_match(event, type, event_id, data, regs))
+                        perf_swevent_event(event, nr, nmi, data, regs);
+        }
+end:
+        rcu_read_unlock();
+}
+
+int perf_swevent_get_recursion_context(void)
+{
+        struct swevent_htable *swhash = &__get_cpu_var(swevent_htable);
+
+        return get_recursion_context(swhash->recursion);
+}
+EXPORT_SYMBOL_GPL(perf_swevent_get_recursion_context);
+
+inline void perf_swevent_put_recursion_context(int rctx)
+{
+        struct swevent_htable *swhash = &__get_cpu_var(swevent_htable);
+
+        put_recursion_context(swhash->recursion, rctx);
+}
+
+void __perf_sw_event(u32 event_id, u64 nr, int nmi,
+                            struct pt_regs *regs, u64 addr)
+{
+        struct perf_sample_data data;
+        int rctx;
+
+        preempt_disable_notrace();
+        rctx = perf_swevent_get_recursion_context();
+        if (rctx < 0)
+                return;
+
+        perf_sample_data_init(&data, addr);
+
+        do_perf_sw_event(PERF_TYPE_SOFTWARE, event_id, nr, nmi, &data, regs);
+
+        perf_swevent_put_recursion_context(rctx);
+        preempt_enable_notrace();
+}
+
+static void perf_swevent_read(struct perf_event *event)
+{
+}
+
+static int perf_swevent_add(struct perf_event *event, int flags)
+{
+        struct swevent_htable *swhash = &__get_cpu_var(swevent_htable);
+        struct hw_perf_event *hwc = &event->hw;
+        struct hlist_head *head;
+
+        if (is_sampling_event(event)) {
+                hwc->last_period = hwc->sample_period;
+                perf_swevent_set_period(event);
+        }
+
+        hwc->state = !(flags & PERF_EF_START);
+
+        head = find_swevent_head(swhash, event);
+        if (WARN_ON_ONCE(!head))
+                return -EINVAL;
+
+        hlist_add_head_rcu(&event->hlist_entry, head);
+
+        return 0;
+}
+
+static void perf_swevent_del(struct perf_event *event, int flags)
+{
+        hlist_del_rcu(&event->hlist_entry);
+}
+
+static void perf_swevent_start(struct perf_event *event, int flags)
+{
+        event->hw.state = 0;
+}
+
+static void perf_swevent_stop(struct perf_event *event, int flags)
+{
+        event->hw.state = PERF_HES_STOPPED;
+}
+
+/* Deref the hlist from the update side */
+static inline struct swevent_hlist *
+swevent_hlist_deref(struct swevent_htable *swhash)
+{
+        return rcu_dereference_protected(swhash->swevent_hlist,
+                                         lockdep_is_held(&swhash->hlist_mutex));
+}
+
+static void swevent_hlist_release_rcu(struct rcu_head *rcu_head)
+{
+        struct swevent_hlist *hlist;
+
+        hlist = container_of(rcu_head, struct swevent_hlist, rcu_head);
+        kfree(hlist);
+}
+
+static void swevent_hlist_release(struct swevent_htable *swhash)
+{
+        struct swevent_hlist *hlist = swevent_hlist_deref(swhash);
+
+        if (!hlist)
+                return;
+
+        rcu_assign_pointer(swhash->swevent_hlist, NULL);
+        call_rcu(&hlist->rcu_head, swevent_hlist_release_rcu);
+}
+
+static void swevent_hlist_put_cpu(struct perf_event *event, int cpu)
+{
+        struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
+
+        mutex_lock(&swhash->hlist_mutex);
+
+        if (!--swhash->hlist_refcount)
+                swevent_hlist_release(swhash);
+
+        mutex_unlock(&swhash->hlist_mutex);
+}
+
+static void swevent_hlist_put(struct perf_event *event)
+{
+        int cpu;
+
+        if (event->cpu != -1) {
+                swevent_hlist_put_cpu(event, event->cpu);
+                return;
+        }
+
+        for_each_possible_cpu(cpu)
+                swevent_hlist_put_cpu(event, cpu);
+}
+
+static int swevent_hlist_get_cpu(struct perf_event *event, int cpu)
+{
+        struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
+        int err = 0;
+
+        mutex_lock(&swhash->hlist_mutex);
+
+        if (!swevent_hlist_deref(swhash) && cpu_online(cpu)) {
+                struct swevent_hlist *hlist;
+
+                hlist = kzalloc(sizeof(*hlist), GFP_KERNEL);
+                if (!hlist) {
+                        err = -ENOMEM;
+                        goto exit;
+                }
+                rcu_assign_pointer(swhash->swevent_hlist, hlist);
+        }
+        swhash->hlist_refcount++;
+exit:
+        mutex_unlock(&swhash->hlist_mutex);
+
+        return err;
+}
+
+static int swevent_hlist_get(struct perf_event *event)
+{
+        int err;
+        int cpu, failed_cpu;
+
+        if (event->cpu != -1)
+                return swevent_hlist_get_cpu(event, event->cpu);
+
+        get_online_cpus();
+        for_each_possible_cpu(cpu) {
+                err = swevent_hlist_get_cpu(event, cpu);
+                if (err) {
+                        failed_cpu = cpu;
+                        goto fail;
+                }
+        }
+        put_online_cpus();
+
+        return 0;
+fail:
+        for_each_possible_cpu(cpu) {
+                if (cpu == failed_cpu)
+                        break;
+                swevent_hlist_put_cpu(event, cpu);
+        }
+
+        put_online_cpus();
+        return err;
+}
+
+struct jump_label_key perf_swevent_enabled[PERF_COUNT_SW_MAX];
+
+static void sw_perf_event_destroy(struct perf_event *event)
+{
+        u64 event_id = event->attr.config;
+
+        WARN_ON(event->parent);
+
+        jump_label_dec(&perf_swevent_enabled[event_id]);
+        swevent_hlist_put(event);
+}
+
+static int perf_swevent_init(struct perf_event *event)
+{
+        int event_id = event->attr.config;
+
+        if (event->attr.type != PERF_TYPE_SOFTWARE)
+                return -ENOENT;
+
+        switch (event_id) {
+        case PERF_COUNT_SW_CPU_CLOCK:
+        case PERF_COUNT_SW_TASK_CLOCK:
+                return -ENOENT;
+
+        default:
+                break;
+        }
+
+        if (event_id >= PERF_COUNT_SW_MAX)
+                return -ENOENT;
+
+        if (!event->parent) {
+                int err;
+
+                err = swevent_hlist_get(event);
+                if (err)
+                        return err;
+
+                jump_label_inc(&perf_swevent_enabled[event_id]);
+                event->destroy = sw_perf_event_destroy;
+        }
+
+        return 0;
+}
+
+static struct pmu perf_swevent = {
+        .task_ctx_nr    = perf_sw_context,
+
+        .event_init     = perf_swevent_init,
+        .add            = perf_swevent_add,
+        .del            = perf_swevent_del,
+        .start          = perf_swevent_start,
+        .stop           = perf_swevent_stop,
+        .read           = perf_swevent_read,
+};
+
+#ifdef CONFIG_EVENT_TRACING
+
+static int perf_tp_filter_match(struct perf_event *event,
+                                struct perf_sample_data *data)
+{
+        void *record = data->raw->data;
+
+        if (likely(!event->filter) || filter_match_preds(event->filter, record))
+                return 1;
+        return 0;
+}
+
+static int perf_tp_event_match(struct perf_event *event,
+                                struct perf_sample_data *data,
+                                struct pt_regs *regs)
+{
+        if (event->hw.state & PERF_HES_STOPPED)
+                return 0;
+        /*
+         * All tracepoints are from kernel-space.
+         */
+        if (event->attr.exclude_kernel)
+                return 0;
+
+        if (!perf_tp_filter_match(event, data))
+                return 0;
+
+        return 1;
+}
+
+void perf_tp_event(u64 addr, u64 count, void *record, int entry_size,
+                   struct pt_regs *regs, struct hlist_head *head, int rctx)
+{
+        struct perf_sample_data data;
+        struct perf_event *event;
+        struct hlist_node *node;
+
+        struct perf_raw_record raw = {
+                .size = entry_size,
+                .data = record,
+        };
+
+        perf_sample_data_init(&data, addr);
+        data.raw = &raw;
+
+        hlist_for_each_entry_rcu(event, node, head, hlist_entry) {
+                if (perf_tp_event_match(event, &data, regs))
+                        perf_swevent_event(event, count, 1, &data, regs);
+        }
+
+        perf_swevent_put_recursion_context(rctx);
+}
+EXPORT_SYMBOL_GPL(perf_tp_event);
+
+static void tp_perf_event_destroy(struct perf_event *event)
+{
+        perf_trace_destroy(event);
+}
+
+static int perf_tp_event_init(struct perf_event *event)
+{
+        int err;
+
+        if (event->attr.type != PERF_TYPE_TRACEPOINT)
+                return -ENOENT;
+
+        err = perf_trace_init(event);
+        if (err)
+                return err;
+
+        event->destroy = tp_perf_event_destroy;
+
+        return 0;
+}
+
+static struct pmu perf_tracepoint = {
+        .task_ctx_nr    = perf_sw_context,
+
+        .event_init     = perf_tp_event_init,
+        .add            = perf_trace_add,
+        .del            = perf_trace_del,
+        .start          = perf_swevent_start,
+        .stop           = perf_swevent_stop,
+        .read           = perf_swevent_read,
+};
+
+static inline void perf_tp_register(void)
+{
+        perf_pmu_register(&perf_tracepoint, "tracepoint", PERF_TYPE_TRACEPOINT);
+}
+
+static int perf_event_set_filter(struct perf_event *event, void __user *arg)
+{
+        char *filter_str;
+        int ret;
+
+        if (event->attr.type != PERF_TYPE_TRACEPOINT)
+                return -EINVAL;
+
+        filter_str = strndup_user(arg, PAGE_SIZE);
+        if (IS_ERR(filter_str))
+                return PTR_ERR(filter_str);
+
+        ret = ftrace_profile_set_filter(event, event->attr.config, filter_str);
+
+        kfree(filter_str);
+        return ret;
+}
+
+static void perf_event_free_filter(struct perf_event *event)
+{
+        ftrace_profile_free_filter(event);
+}
+
+#else
+
+static inline void perf_tp_register(void)
+{
+}
+
+static int perf_event_set_filter(struct perf_event *event, void __user *arg)
+{
+        return -ENOENT;
+}
+
+static void perf_event_free_filter(struct perf_event *event)
+{
+}
+
+#endif /* CONFIG_EVENT_TRACING */
+
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+void perf_bp_event(struct perf_event *bp, void *data)
+{
+        struct perf_sample_data sample;
+        struct pt_regs *regs = data;
+
+        perf_sample_data_init(&sample, bp->attr.bp_addr);
+
+        if (!bp->hw.state && !perf_exclude_event(bp, regs))
+                perf_swevent_event(bp, 1, 1, &sample, regs);
+}
+#endif
+
+/*
+ * hrtimer based swevent callback
+ */
+
+static enum hrtimer_restart perf_swevent_hrtimer(struct hrtimer *hrtimer)
+{
+        enum hrtimer_restart ret = HRTIMER_RESTART;
+        struct perf_sample_data data;
+        struct pt_regs *regs;
+        struct perf_event *event;
+        u64 period;
+
+        event = container_of(hrtimer, struct perf_event, hw.hrtimer);
+
+        if (event->state != PERF_EVENT_STATE_ACTIVE)
+                return HRTIMER_NORESTART;
+
+        event->pmu->read(event);
+
+        perf_sample_data_init(&data, 0);
+        data.period = event->hw.last_period;
+        regs = get_irq_regs();
+
+        if (regs && !perf_exclude_event(event, regs)) {
+                if (!(event->attr.exclude_idle && current->pid == 0))
+                        if (perf_event_overflow(event, 0, &data, regs))
+                                ret = HRTIMER_NORESTART;
+        }
+
+        period = max_t(u64, 10000, event->hw.sample_period);
+        hrtimer_forward_now(hrtimer, ns_to_ktime(period));
+
+        return ret;
+}
+
+static void perf_swevent_start_hrtimer(struct perf_event *event)
+{
+        struct hw_perf_event *hwc = &event->hw;
+        s64 period;
+
+        if (!is_sampling_event(event))
+                return;
+
+        period = local64_read(&hwc->period_left);
+        if (period) {
+                if (period < 0)
+                        period = 10000;
+
+                local64_set(&hwc->period_left, 0);
+        } else {
+                period = max_t(u64, 10000, hwc->sample_period);
+        }
+        __hrtimer_start_range_ns(&hwc->hrtimer,
+                                ns_to_ktime(period), 0,
+                                HRTIMER_MODE_REL_PINNED, 0);
+}
+
+static void perf_swevent_cancel_hrtimer(struct perf_event *event)
+{
+        struct hw_perf_event *hwc = &event->hw;
+
+        if (is_sampling_event(event)) {
+                ktime_t remaining = hrtimer_get_remaining(&hwc->hrtimer);
+                local64_set(&hwc->period_left, ktime_to_ns(remaining));
+
+                hrtimer_cancel(&hwc->hrtimer);
+        }
+}
+
+static void perf_swevent_init_hrtimer(struct perf_event *event)
+{
+        struct hw_perf_event *hwc = &event->hw;
+
+        if (!is_sampling_event(event))
+                return;
+
+        hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+        hwc->hrtimer.function = perf_swevent_hrtimer;
+
+        /*
+         * Since hrtimers have a fixed rate, we can do a static freq->period
+         * mapping and avoid the whole period adjust feedback stuff.
+         */
+        if (event->attr.freq) {
+                long freq = event->attr.sample_freq;
+
+                event->attr.sample_period = NSEC_PER_SEC / freq;
+                hwc->sample_period = event->attr.sample_period;
+                local64_set(&hwc->period_left, hwc->sample_period);
+                event->attr.freq = 0;
+        }
+}
+
+/*
+ * Software event: cpu wall time clock
+ */
+
+static void cpu_clock_event_update(struct perf_event *event)
+{
+        s64 prev;
+        u64 now;
+
+        now = local_clock();
+        prev = local64_xchg(&event->hw.prev_count, now);
+        local64_add(now - prev, &event->count);
+}
+
+static void cpu_clock_event_start(struct perf_event *event, int flags)
+{
+        local64_set(&event->hw.prev_count, local_clock());
+        perf_swevent_start_hrtimer(event);
+}
+
+static void cpu_clock_event_stop(struct perf_event *event, int flags)
+{
+        perf_swevent_cancel_hrtimer(event);
+        cpu_clock_event_update(event);
+}
+
+static int cpu_clock_event_add(struct perf_event *event, int flags)
+{
+        if (flags & PERF_EF_START)
+                cpu_clock_event_start(event, flags);
+
+        return 0;
+}
+
+static void cpu_clock_event_del(struct perf_event *event, int flags)
+{
+        cpu_clock_event_stop(event, flags);
+}
+
+static void cpu_clock_event_read(struct perf_event *event)
+{
+        cpu_clock_event_update(event);
+}
+
+static int cpu_clock_event_init(struct perf_event *event)
+{
+        if (event->attr.type != PERF_TYPE_SOFTWARE)
+                return -ENOENT;
+
+        if (event->attr.config != PERF_COUNT_SW_CPU_CLOCK)
+                return -ENOENT;
+
+        perf_swevent_init_hrtimer(event);
+
+        return 0;
+}
+
+static struct pmu perf_cpu_clock = {
+        .task_ctx_nr    = perf_sw_context,
+
+        .event_init     = cpu_clock_event_init,
+        .add            = cpu_clock_event_add,
+        .del            = cpu_clock_event_del,
+        .start          = cpu_clock_event_start,
+        .stop           = cpu_clock_event_stop,
+        .read           = cpu_clock_event_read,
+};
+
+/*
+ * Software event: task time clock
+ */
+
+static void task_clock_event_update(struct perf_event *event, u64 now)
+{
+        u64 prev;
+        s64 delta;
+
+        prev = local64_xchg(&event->hw.prev_count, now);
+        delta = now - prev;
+        local64_add(delta, &event->count);
+}
+
+static void task_clock_event_start(struct perf_event *event, int flags)
+{
+        local64_set(&event->hw.prev_count, event->ctx->time);
+        perf_swevent_start_hrtimer(event);
+}
+
+static void task_clock_event_stop(struct perf_event *event, int flags)
+{
+        perf_swevent_cancel_hrtimer(event);
+        task_clock_event_update(event, event->ctx->time);
+}
+
+static int task_clock_event_add(struct perf_event *event, int flags)
+{
+        if (flags & PERF_EF_START)
+                task_clock_event_start(event, flags);
+
+        return 0;
+}
+
+static void task_clock_event_del(struct perf_event *event, int flags)
+{
+        task_clock_event_stop(event, PERF_EF_UPDATE);
+}
+
+static void task_clock_event_read(struct perf_event *event)
+{
+        u64 now = perf_clock();
+        u64 delta = now - event->ctx->timestamp;
+        u64 time = event->ctx->time + delta;
+
+        task_clock_event_update(event, time);
+}
+
+static int task_clock_event_init(struct perf_event *event)
+{
+        if (event->attr.type != PERF_TYPE_SOFTWARE)
+                return -ENOENT;
+
+        if (event->attr.config != PERF_COUNT_SW_TASK_CLOCK)
+                return -ENOENT;
+
+        perf_swevent_init_hrtimer(event);
+
+        return 0;
+}
+
+static struct pmu perf_task_clock = {
+        .task_ctx_nr    = perf_sw_context,
+
+        .event_init     = task_clock_event_init,
+        .add            = task_clock_event_add,
+        .del            = task_clock_event_del,
+        .start          = task_clock_event_start,
+        .stop           = task_clock_event_stop,
+        .read           = task_clock_event_read,
+};
+
+static void perf_pmu_nop_void(struct pmu *pmu)
+{
+}
+
+static int perf_pmu_nop_int(struct pmu *pmu)
+{
+        return 0;
+}
+
+static void perf_pmu_start_txn(struct pmu *pmu)
+{
+        perf_pmu_disable(pmu);
+}
+
+static int perf_pmu_commit_txn(struct pmu *pmu)
+{
+        perf_pmu_enable(pmu);
+        return 0;
+}
+
+static void perf_pmu_cancel_txn(struct pmu *pmu)
+{
+        perf_pmu_enable(pmu);
+}
+
+/*
+ * Ensures all contexts with the same task_ctx_nr have the same
+ * pmu_cpu_context too.
+ */
+static void *find_pmu_context(int ctxn)
+{
+        struct pmu *pmu;
+
+        if (ctxn < 0)
+                return NULL;
+
+        list_for_each_entry(pmu, &pmus, entry) {
+                if (pmu->task_ctx_nr == ctxn)
+                        return pmu->pmu_cpu_context;
+        }
+
+        return NULL;
+}
+
+static void update_pmu_context(struct pmu *pmu, struct pmu *old_pmu)
+{
+        int cpu;
+
+        for_each_possible_cpu(cpu) {
+                struct perf_cpu_context *cpuctx;
+
+                cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+
+                if (cpuctx->active_pmu == old_pmu)
+                        cpuctx->active_pmu = pmu;
+        }
+}
+
+static void free_pmu_context(struct pmu *pmu)
+{
+        struct pmu *i;
+
+        mutex_lock(&pmus_lock);
+        /*
+         * Like a real lame refcount.
+         */
+        list_for_each_entry(i, &pmus, entry) {
+                if (i->pmu_cpu_context == pmu->pmu_cpu_context) {
+                        update_pmu_context(i, pmu);
+                        goto out;
+                }
+        }
+
+        free_percpu(pmu->pmu_cpu_context);
+out:
+        mutex_unlock(&pmus_lock);
+}
+static struct idr pmu_idr;
+
+static ssize_t
+type_show(struct device *dev, struct device_attribute *attr, char *page)
+{
+        struct pmu *pmu = dev_get_drvdata(dev);
+
+        return snprintf(page, PAGE_SIZE-1, "%d\n", pmu->type);
+}
+
+static struct device_attribute pmu_dev_attrs[] = {
+       __ATTR_RO(type),
+       __ATTR_NULL,
+};
+
+static int pmu_bus_running;
+static struct bus_type pmu_bus = {
+        .name           = "event_source",
+        .dev_attrs      = pmu_dev_attrs,
+};
+
+static void pmu_dev_release(struct device *dev)
+{
+        kfree(dev);
+}
+
+static int pmu_dev_alloc(struct pmu *pmu)
+{
+        int ret = -ENOMEM;
+
+        pmu->dev = kzalloc(sizeof(struct device), GFP_KERNEL);
+        if (!pmu->dev)
+                goto out;
+
+        device_initialize(pmu->dev);
+        ret = dev_set_name(pmu->dev, "%s", pmu->name);
+        if (ret)
+                goto free_dev;
+
+        dev_set_drvdata(pmu->dev, pmu);
+        pmu->dev->bus = &pmu_bus;
+        pmu->dev->release = pmu_dev_release;
+        ret = device_add(pmu->dev);
+        if (ret)
+                goto free_dev;
+
+out:
+        return ret;
+
+free_dev:
+        put_device(pmu->dev);
+        goto out;
+}
+
+static struct lock_class_key cpuctx_mutex;
+
+int perf_pmu_register(struct pmu *pmu, char *name, int type)
+{
+        int cpu, ret;
+
+        mutex_lock(&pmus_lock);
+        ret = -ENOMEM;
+        pmu->pmu_disable_count = alloc_percpu(int);
+        if (!pmu->pmu_disable_count)
+                goto unlock;
+
+        pmu->type = -1;
+        if (!name)
+                goto skip_type;
+        pmu->name = name;
+
+        if (type < 0) {
+                int err = idr_pre_get(&pmu_idr, GFP_KERNEL);
+                if (!err)
+                        goto free_pdc;
+
+                err = idr_get_new_above(&pmu_idr, pmu, PERF_TYPE_MAX, &type);
+                if (err) {
+                        ret = err;
+                        goto free_pdc;
+                }
+        }
+        pmu->type = type;
+
+        if (pmu_bus_running) {
+                ret = pmu_dev_alloc(pmu);
+                if (ret)
+                        goto free_idr;
+        }
+
+skip_type:
+        pmu->pmu_cpu_context = find_pmu_context(pmu->task_ctx_nr);
+        if (pmu->pmu_cpu_context)
+                goto got_cpu_context;
+
+        pmu->pmu_cpu_context = alloc_percpu(struct perf_cpu_context);
+        if (!pmu->pmu_cpu_context)
+                goto free_dev;
+
+        for_each_possible_cpu(cpu) {
+                struct perf_cpu_context *cpuctx;
+
+                cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+                __perf_event_init_context(&cpuctx->ctx);
+                lockdep_set_class(&cpuctx->ctx.mutex, &cpuctx_mutex);
+                cpuctx->ctx.type = cpu_context;
+                cpuctx->ctx.pmu = pmu;
+                cpuctx->jiffies_interval = 1;
+                INIT_LIST_HEAD(&cpuctx->rotation_list);
+                cpuctx->active_pmu = pmu;
+        }
+
+got_cpu_context:
+        if (!pmu->start_txn) {
+                if (pmu->pmu_enable) {
+                        /*
+                         * If we have pmu_enable/pmu_disable calls, install
+                         * transaction stubs that use that to try and batch
+                         * hardware accesses.
+                         */
+                        pmu->start_txn  = perf_pmu_start_txn;
+                        pmu->commit_txn = perf_pmu_commit_txn;
+                        pmu->cancel_txn = perf_pmu_cancel_txn;
+                } else {
+                        pmu->start_txn  = perf_pmu_nop_void;
+                        pmu->commit_txn = perf_pmu_nop_int;
+                        pmu->cancel_txn = perf_pmu_nop_void;
+                }
+        }
+
+        if (!pmu->pmu_enable) {
+                pmu->pmu_enable  = perf_pmu_nop_void;
+                pmu->pmu_disable = perf_pmu_nop_void;
+        }
+
+        list_add_rcu(&pmu->entry, &pmus);
+        ret = 0;
+unlock:
+        mutex_unlock(&pmus_lock);
+
+        return ret;
+
+free_dev:
+        device_del(pmu->dev);
+        put_device(pmu->dev);
+
+free_idr:
+        if (pmu->type >= PERF_TYPE_MAX)
+                idr_remove(&pmu_idr, pmu->type);
+
+free_pdc:
+        free_percpu(pmu->pmu_disable_count);
+        goto unlock;
+}
+
+void perf_pmu_unregister(struct pmu *pmu)
+{
+        mutex_lock(&pmus_lock);
+        list_del_rcu(&pmu->entry);
+        mutex_unlock(&pmus_lock);
+
+        /*
+         * We dereference the pmu list under both SRCU and regular RCU, so
+         * synchronize against both of those.
+         */
+        synchronize_srcu(&pmus_srcu);
+        synchronize_rcu();
+
+        free_percpu(pmu->pmu_disable_count);
+        if (pmu->type >= PERF_TYPE_MAX)
+                idr_remove(&pmu_idr, pmu->type);
+        device_del(pmu->dev);
+        put_device(pmu->dev);
+        free_pmu_context(pmu);
+}
+
+struct pmu *perf_init_event(struct perf_event *event)
+{
+        struct pmu *pmu = NULL;
+        int idx;
+        int ret;
+
+        idx = srcu_read_lock(&pmus_srcu);
+
+        rcu_read_lock();
+        pmu = idr_find(&pmu_idr, event->attr.type);
+        rcu_read_unlock();
+        if (pmu) {
+                ret = pmu->event_init(event);
+                if (ret)
+                        pmu = ERR_PTR(ret);
+                goto unlock;
+        }
+
+        list_for_each_entry_rcu(pmu, &pmus, entry) {
+                ret = pmu->event_init(event);
+                if (!ret)
+                        goto unlock;
+
+                if (ret != -ENOENT) {
+                        pmu = ERR_PTR(ret);
+                        goto unlock;
+                }
+        }
+        pmu = ERR_PTR(-ENOENT);
+unlock:
+        srcu_read_unlock(&pmus_srcu, idx);
+
+        return pmu;
+}
+
+/*
+ * Allocate and initialize a event structure
+ */
+static struct perf_event *
+perf_event_alloc(struct perf_event_attr *attr, int cpu,
+                 struct task_struct *task,
+                 struct perf_event *group_leader,
+                 struct perf_event *parent_event,
+                 perf_overflow_handler_t overflow_handler)
+{
+        struct pmu *pmu;
+        struct perf_event *event;
+        struct hw_perf_event *hwc;
+        long err;
+
+        if ((unsigned)cpu >= nr_cpu_ids) {
+                if (!task || cpu != -1)
+                        return ERR_PTR(-EINVAL);
+        }
+
+        event = kzalloc(sizeof(*event), GFP_KERNEL);
+        if (!event)
+                return ERR_PTR(-ENOMEM);
+
+        /*
+         * Single events are their own group leaders, with an
+         * empty sibling list:
+         */
+        if (!group_leader)
+                group_leader = event;
+
+        mutex_init(&event->child_mutex);
+        INIT_LIST_HEAD(&event->child_list);
+
+        INIT_LIST_HEAD(&event->group_entry);
+        INIT_LIST_HEAD(&event->event_entry);
+        INIT_LIST_HEAD(&event->sibling_list);
+        init_waitqueue_head(&event->waitq);
+        init_irq_work(&event->pending, perf_pending_event);
+
+        mutex_init(&event->mmap_mutex);
+
+        event->cpu              = cpu;
+        event->attr             = *attr;
+        event->group_leader     = group_leader;
+        event->pmu              = NULL;
+        event->oncpu            = -1;
+
+        event->parent           = parent_event;
+
+        event->ns               = get_pid_ns(current->nsproxy->pid_ns);
+        event->id               = atomic64_inc_return(&perf_event_id);
+
+        event->state            = PERF_EVENT_STATE_INACTIVE;
+
+        if (task) {
+                event->attach_state = PERF_ATTACH_TASK;
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+                /*
+                 * hw_breakpoint is a bit difficult here..
+                 */
+                if (attr->type == PERF_TYPE_BREAKPOINT)
+                        event->hw.bp_target = task;
+#endif
+        }
+
+        if (!overflow_handler && parent_event)
+                overflow_handler = parent_event->overflow_handler;
+
+        event->overflow_handler = overflow_handler;
+
+        if (attr->disabled)
+                event->state = PERF_EVENT_STATE_OFF;
+
+        pmu = NULL;
+
+        hwc = &event->hw;
+        hwc->sample_period = attr->sample_period;
+        if (attr->freq && attr->sample_freq)
+                hwc->sample_period = 1;
+        hwc->last_period = hwc->sample_period;
+
+        local64_set(&hwc->period_left, hwc->sample_period);
+
+        /*
+         * we currently do not support PERF_FORMAT_GROUP on inherited events
+         */
+        if (attr->inherit && (attr->read_format & PERF_FORMAT_GROUP))
+                goto done;
+
+        pmu = perf_init_event(event);
+
+done:
+        err = 0;
+        if (!pmu)
+                err = -EINVAL;
+        else if (IS_ERR(pmu))
+                err = PTR_ERR(pmu);
+
+        if (err) {
+                if (event->ns)
+                        put_pid_ns(event->ns);
+                kfree(event);
+                return ERR_PTR(err);
+        }
+
+        event->pmu = pmu;
+
+        if (!event->parent) {
+                if (event->attach_state & PERF_ATTACH_TASK)
+                        jump_label_inc(&perf_sched_events);
+                if (event->attr.mmap || event->attr.mmap_data)
+                        atomic_inc(&nr_mmap_events);
+                if (event->attr.comm)
+                        atomic_inc(&nr_comm_events);
+                if (event->attr.task)
+                        atomic_inc(&nr_task_events);
+                if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) {
+                        err = get_callchain_buffers();
+                        if (err) {
+                                free_event(event);
+                                return ERR_PTR(err);
+                        }
+                }
+        }
+
+        return event;
+}
+
+static int perf_copy_attr(struct perf_event_attr __user *uattr,
+                          struct perf_event_attr *attr)
+{
+        u32 size;
+        int ret;
+
+        if (!access_ok(VERIFY_WRITE, uattr, PERF_ATTR_SIZE_VER0))
+                return -EFAULT;
+
+        /*
+         * zero the full structure, so that a short copy will be nice.
+         */
+        memset(attr, 0, sizeof(*attr));
+
+        ret = get_user(size, &uattr->size);
+        if (ret)
+                return ret;
+
+        if (size > PAGE_SIZE)   /* silly large */
+                goto err_size;
+
+        if (!size)              /* abi compat */
+                size = PERF_ATTR_SIZE_VER0;
+
+        if (size < PERF_ATTR_SIZE_VER0)
+                goto err_size;
+
+        /*
+         * If we're handed a bigger struct than we know of,
+         * ensure all the unknown bits are 0 - i.e. new
+         * user-space does not rely on any kernel feature
+         * extensions we dont know about yet.
+         */
+        if (size > sizeof(*attr)) {
+                unsigned char __user *addr;
+                unsigned char __user *end;
+                unsigned char val;
+
+                addr = (void __user *)uattr + sizeof(*attr);
+                end  = (void __user *)uattr + size;
+
+                for (; addr < end; addr++) {
+                        ret = get_user(val, addr);
+                        if (ret)
+                                return ret;
+                        if (val)
+                                goto err_size;
+                }
+                size = sizeof(*attr);
+        }
+
+        ret = copy_from_user(attr, uattr, size);
+        if (ret)
+                return -EFAULT;
+
+        /*
+         * If the type exists, the corresponding creation will verify
+         * the attr->config.
+         */
+        if (attr->type >= PERF_TYPE_MAX)
+                return -EINVAL;
+
+        if (attr->__reserved_1)
+                return -EINVAL;
+
+        if (attr->sample_type & ~(PERF_SAMPLE_MAX-1))
+                return -EINVAL;
+
+        if (attr->read_format & ~(PERF_FORMAT_MAX-1))
+                return -EINVAL;
+
+out:
+        return ret;
+
+err_size:
+        put_user(sizeof(*attr), &uattr->size);
+        ret = -E2BIG;
+        goto out;
+}
+
+static int
+perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
+{
+        struct perf_buffer *buffer = NULL, *old_buffer = NULL;
+        int ret = -EINVAL;
+
+        if (!output_event)
+                goto set;
+
+        /* don't allow circular references */
+        if (event == output_event)
+                goto out;
+
+        /*
+         * Don't allow cross-cpu buffers
+         */
+        if (output_event->cpu != event->cpu)
+                goto out;
+
+        /*
+         * If its not a per-cpu buffer, it must be the same task.
+         */
+        if (output_event->cpu == -1 && output_event->ctx != event->ctx)
+                goto out;
+
+set:
+        mutex_lock(&event->mmap_mutex);
+        /* Can't redirect output if we've got an active mmap() */
+        if (atomic_read(&event->mmap_count))
+                goto unlock;
+
+        if (output_event) {
+                /* get the buffer we want to redirect to */
+                buffer = perf_buffer_get(output_event);
+                if (!buffer)
+                        goto unlock;
+        }
+
+        old_buffer = event->buffer;
+        rcu_assign_pointer(event->buffer, buffer);
+        ret = 0;
+unlock:
+        mutex_unlock(&event->mmap_mutex);
+
+        if (old_buffer)
+                perf_buffer_put(old_buffer);
+out:
+        return ret;
+}
+
+/**
+ * sys_perf_event_open - open a performance event, associate it to a task/cpu
+ *
+ * @attr_uptr:  event_id type attributes for monitoring/sampling
+ * @pid:                target pid
+ * @cpu:                target cpu
+ * @group_fd:           group leader event fd
+ */
+SYSCALL_DEFINE5(perf_event_open,
+                struct perf_event_attr __user *, attr_uptr,
+                pid_t, pid, int, cpu, int, group_fd, unsigned long, flags)
+{
+        struct perf_event *group_leader = NULL, *output_event = NULL;
+        struct perf_event *event, *sibling;
+        struct perf_event_attr attr;
+        struct perf_event_context *ctx;
+        struct file *event_file = NULL;
+        struct file *group_file = NULL;
+        struct task_struct *task = NULL;
+        struct pmu *pmu;
+        int event_fd;
+        int move_group = 0;
+        int fput_needed = 0;
+        int err;
+
+        /* for future expandability... */
+        if (flags & ~PERF_FLAG_ALL)
+                return -EINVAL;
+
+        err = perf_copy_attr(attr_uptr, &attr);
+        if (err)
+                return err;
+
+        if (!attr.exclude_kernel) {
+                if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
+                        return -EACCES;
+        }
+
+        if (attr.freq) {
+                if (attr.sample_freq > sysctl_perf_event_sample_rate)
+                        return -EINVAL;
+        }
+
+        /*
+         * In cgroup mode, the pid argument is used to pass the fd
+         * opened to the cgroup directory in cgroupfs. The cpu argument
+         * designates the cpu on which to monitor threads from that
+         * cgroup.
+         */
+        if ((flags & PERF_FLAG_PID_CGROUP) && (pid == -1 || cpu == -1))
+                return -EINVAL;
+
+        event_fd = get_unused_fd_flags(O_RDWR);
+        if (event_fd < 0)
+                return event_fd;
+
+        if (group_fd != -1) {
+                group_leader = perf_fget_light(group_fd, &fput_needed);
+                if (IS_ERR(group_leader)) {
+                        err = PTR_ERR(group_leader);
+                        goto err_fd;
+                }
+                group_file = group_leader->filp;
+                if (flags & PERF_FLAG_FD_OUTPUT)
+                        output_event = group_leader;
+                if (flags & PERF_FLAG_FD_NO_GROUP)
+                        group_leader = NULL;
+        }
+
+        if (pid != -1 && !(flags & PERF_FLAG_PID_CGROUP)) {
+                task = find_lively_task_by_vpid(pid);
+                if (IS_ERR(task)) {
+                        err = PTR_ERR(task);
+                        goto err_group_fd;
+                }
+        }
+
+        event = perf_event_alloc(&attr, cpu, task, group_leader, NULL, NULL);
+        if (IS_ERR(event)) {
+                err = PTR_ERR(event);
+                goto err_task;
+        }
+
+        if (flags & PERF_FLAG_PID_CGROUP) {
+                err = perf_cgroup_connect(pid, event, &attr, group_leader);
+                if (err)
+                        goto err_alloc;
+                /*
+                 * one more event:
+                 * - that has cgroup constraint on event->cpu
+                 * - that may need work on context switch
+                 */
+                atomic_inc(&per_cpu(perf_cgroup_events, event->cpu));
+                jump_label_inc(&perf_sched_events);
+        }
+
+        /*
+         * Special case software events and allow them to be part of
+         * any hardware group.
+         */
+        pmu = event->pmu;
+
+        if (group_leader &&
+            (is_software_event(event) != is_software_event(group_leader))) {
+                if (is_software_event(event)) {
+                        /*
+                         * If event and group_leader are not both a software
+                         * event, and event is, then group leader is not.
+                         *
+                         * Allow the addition of software events to !software
+                         * groups, this is safe because software events never
+                         * fail to schedule.
+                         */
+                        pmu = group_leader->pmu;
+                } else if (is_software_event(group_leader) &&
+                           (group_leader->group_flags & PERF_GROUP_SOFTWARE)) {
+                        /*
+                         * In case the group is a pure software group, and we
+                         * try to add a hardware event, move the whole group to
+                         * the hardware context.
+                         */
+                        move_group = 1;
+                }
+        }
+
+        /*
+         * Get the target context (task or percpu):
+         */
+        ctx = find_get_context(pmu, task, cpu);
+        if (IS_ERR(ctx)) {
+                err = PTR_ERR(ctx);
+                goto err_alloc;
+        }
+
+        if (task) {
+                put_task_struct(task);
+                task = NULL;
+        }
+
+        /*
+         * Look up the group leader (we will attach this event to it):
+         */
+        if (group_leader) {
+                err = -EINVAL;
+
+                /*
+                 * Do not allow a recursive hierarchy (this new sibling
+                 * becoming part of another group-sibling):
+                 */
+                if (group_leader->group_leader != group_leader)
+                        goto err_context;
+                /*
+                 * Do not allow to attach to a group in a different
+                 * task or CPU context:
+                 */
+                if (move_group) {
+                        if (group_leader->ctx->type != ctx->type)
+                                goto err_context;
+                } else {
+                        if (group_leader->ctx != ctx)
+                                goto err_context;
+                }
+
+                /*
+                 * Only a group leader can be exclusive or pinned
+                 */
+                if (attr.exclusive || attr.pinned)
+                        goto err_context;
+        }
+
+        if (output_event) {
+                err = perf_event_set_output(event, output_event);
+                if (err)
+                        goto err_context;
+        }
+
+        event_file = anon_inode_getfile("[perf_event]", &perf_fops, event, O_RDWR);
+        if (IS_ERR(event_file)) {
+                err = PTR_ERR(event_file);
+                goto err_context;
+        }
+
+        if (move_group) {
+                struct perf_event_context *gctx = group_leader->ctx;
+
+                mutex_lock(&gctx->mutex);
+                perf_remove_from_context(group_leader);
+                list_for_each_entry(sibling, &group_leader->sibling_list,
+                                    group_entry) {
+                        perf_remove_from_context(sibling);
+                        put_ctx(gctx);
+                }
+                mutex_unlock(&gctx->mutex);
+                put_ctx(gctx);
+        }
+
+        event->filp = event_file;
+        WARN_ON_ONCE(ctx->parent_ctx);
+        mutex_lock(&ctx->mutex);
+
+        if (move_group) {
+                perf_install_in_context(ctx, group_leader, cpu);
+                get_ctx(ctx);
+                list_for_each_entry(sibling, &group_leader->sibling_list,
+                                    group_entry) {
+                        perf_install_in_context(ctx, sibling, cpu);
+                        get_ctx(ctx);
+                }
+        }
+
+        perf_install_in_context(ctx, event, cpu);
+        ++ctx->generation;
+        perf_unpin_context(ctx);
+        mutex_unlock(&ctx->mutex);
+
+        event->owner = current;
+
+        mutex_lock(&current->perf_event_mutex);
+        list_add_tail(&event->owner_entry, &current->perf_event_list);
+        mutex_unlock(&current->perf_event_mutex);
+
+        /*
+         * Precalculate sample_data sizes
+         */
+        perf_event__header_size(event);
+        perf_event__id_header_size(event);
+
+        /*
+         * Drop the reference on the group_event after placing the
+         * new event on the sibling_list. This ensures destruction
+         * of the group leader will find the pointer to itself in
+         * perf_group_detach().
+         */
+        fput_light(group_file, fput_needed);
+        fd_install(event_fd, event_file);
+        return event_fd;
+
+err_context:
+        perf_unpin_context(ctx);
+        put_ctx(ctx);
+err_alloc:
+        free_event(event);
+err_task:
+        if (task)
+                put_task_struct(task);
+err_group_fd:
+        fput_light(group_file, fput_needed);
+err_fd:
+        put_unused_fd(event_fd);
+        return err;
+}
+
+/**
+ * perf_event_create_kernel_counter
+ *
+ * @attr: attributes of the counter to create
+ * @cpu: cpu in which the counter is bound
+ * @task: task to profile (NULL for percpu)
+ */
+struct perf_event *
+perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
+                                 struct task_struct *task,
+                                 perf_overflow_handler_t overflow_handler)
+{
+        struct perf_event_context *ctx;
+        struct perf_event *event;
+        int err;
+
+        /*
+         * Get the target context (task or percpu):
+         */
+
+        event = perf_event_alloc(attr, cpu, task, NULL, NULL, overflow_handler);
+        if (IS_ERR(event)) {
+                err = PTR_ERR(event);
+                goto err;
+        }
+
+        ctx = find_get_context(event->pmu, task, cpu);
+        if (IS_ERR(ctx)) {
+                err = PTR_ERR(ctx);
+                goto err_free;
+        }
+
+        event->filp = NULL;
+        WARN_ON_ONCE(ctx->parent_ctx);
+        mutex_lock(&ctx->mutex);
+        perf_install_in_context(ctx, event, cpu);
+        ++ctx->generation;
+        perf_unpin_context(ctx);
+        mutex_unlock(&ctx->mutex);
+
+        return event;
+
+err_free:
+        free_event(event);
+err:
+        return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(perf_event_create_kernel_counter);
+
+static void sync_child_event(struct perf_event *child_event,
+                               struct task_struct *child)
+{
+        struct perf_event *parent_event = child_event->parent;
+        u64 child_val;
+
+        if (child_event->attr.inherit_stat)
+                perf_event_read_event(child_event, child);
+
+        child_val = perf_event_count(child_event);
+
+        /*
+         * Add back the child's count to the parent's count:
+         */
+        atomic64_add(child_val, &parent_event->child_count);
+        atomic64_add(child_event->total_time_enabled,
+                     &parent_event->child_total_time_enabled);
+        atomic64_add(child_event->total_time_running,
+                     &parent_event->child_total_time_running);
+
+        /*
+         * Remove this event from the parent's list
+         */
+        WARN_ON_ONCE(parent_event->ctx->parent_ctx);
+        mutex_lock(&parent_event->child_mutex);
+        list_del_init(&child_event->child_list);
+        mutex_unlock(&parent_event->child_mutex);
+
+        /*
+         * Release the parent event, if this was the last
+         * reference to it.
+         */
+        fput(parent_event->filp);
+}
+
+static void
+__perf_event_exit_task(struct perf_event *child_event,
+                         struct perf_event_context *child_ctx,
+                         struct task_struct *child)
+{
+        if (child_event->parent) {
+                raw_spin_lock_irq(&child_ctx->lock);
+                perf_group_detach(child_event);
+                raw_spin_unlock_irq(&child_ctx->lock);
+        }
+
+        perf_remove_from_context(child_event);
+
+        /*
+         * It can happen that the parent exits first, and has events
+         * that are still around due to the child reference. These
+         * events need to be zapped.
+         */
+        if (child_event->parent) {
+                sync_child_event(child_event, child);
+                free_event(child_event);
+        }
+}
+
+static void perf_event_exit_task_context(struct task_struct *child, int ctxn)
+{
+        struct perf_event *child_event, *tmp;
+        struct perf_event_context *child_ctx;
+        unsigned long flags;
+
+        if (likely(!child->perf_event_ctxp[ctxn])) {
+                perf_event_task(child, NULL, 0);
+                return;
+        }
+
+        local_irq_save(flags);
+        /*
+         * We can't reschedule here because interrupts are disabled,
+         * and either child is current or it is a task that can't be
+         * scheduled, so we are now safe from rescheduling changing
+         * our context.
+         */
+        child_ctx = rcu_dereference_raw(child->perf_event_ctxp[ctxn]);
+        task_ctx_sched_out(child_ctx, EVENT_ALL);
+
+        /*
+         * Take the context lock here so that if find_get_context is
+         * reading child->perf_event_ctxp, we wait until it has
+         * incremented the context's refcount before we do put_ctx below.
+         */
+        raw_spin_lock(&child_ctx->lock);
+        child->perf_event_ctxp[ctxn] = NULL;
+        /*
+         * If this context is a clone; unclone it so it can't get
+         * swapped to another process while we're removing all
+         * the events from it.
+         */
+        unclone_ctx(child_ctx);
+        update_context_time(child_ctx);
+        raw_spin_unlock_irqrestore(&child_ctx->lock, flags);
+
+        /*
+         * Report the task dead after unscheduling the events so that we
+         * won't get any samples after PERF_RECORD_EXIT. We can however still
+         * get a few PERF_RECORD_READ events.
+         */
+        perf_event_task(child, child_ctx, 0);
+
+        /*
+         * We can recurse on the same lock type through:
+         *
+         *   __perf_event_exit_task()
+         *     sync_child_event()
+         *       fput(parent_event->filp)
+         *         perf_release()
+         *           mutex_lock(&ctx->mutex)
+         *
+         * But since its the parent context it won't be the same instance.
+         */
+        mutex_lock(&child_ctx->mutex);
+
+again:
+        list_for_each_entry_safe(child_event, tmp, &child_ctx->pinned_groups,
+                                 group_entry)
+                __perf_event_exit_task(child_event, child_ctx, child);
+
+        list_for_each_entry_safe(child_event, tmp, &child_ctx->flexible_groups,
+                                 group_entry)
+                __perf_event_exit_task(child_event, child_ctx, child);
+
+        /*
+         * If the last event was a group event, it will have appended all
+         * its siblings to the list, but we obtained 'tmp' before that which
+         * will still point to the list head terminating the iteration.
+         */
+        if (!list_empty(&child_ctx->pinned_groups) ||
+            !list_empty(&child_ctx->flexible_groups))
+                goto again;
+
+        mutex_unlock(&child_ctx->mutex);
+
+        put_ctx(child_ctx);
+}
+
+/*
+ * When a child task exits, feed back event values to parent events.
+ */
+void perf_event_exit_task(struct task_struct *child)
+{
+        struct perf_event *event, *tmp;
+        int ctxn;
+
+        mutex_lock(&child->perf_event_mutex);
+        list_for_each_entry_safe(event, tmp, &child->perf_event_list,
+                                 owner_entry) {
+                list_del_init(&event->owner_entry);
+
+                /*
+                 * Ensure the list deletion is visible before we clear
+                 * the owner, closes a race against perf_release() where
+                 * we need to serialize on the owner->perf_event_mutex.
+                 */
+                smp_wmb();
+                event->owner = NULL;
+        }
+        mutex_unlock(&child->perf_event_mutex);
+
+        for_each_task_context_nr(ctxn)
+                perf_event_exit_task_context(child, ctxn);
+}
+
+static void perf_free_event(struct perf_event *event,
+                            struct perf_event_context *ctx)
+{
+        struct perf_event *parent = event->parent;
+
+        if (WARN_ON_ONCE(!parent))
+                return;
+
+        mutex_lock(&parent->child_mutex);
+        list_del_init(&event->child_list);
+        mutex_unlock(&parent->child_mutex);
+
+        fput(parent->filp);
+
+        perf_group_detach(event);
+        list_del_event(event, ctx);
+        free_event(event);
+}
+
+/*
+ * free an unexposed, unused context as created by inheritance by
+ * perf_event_init_task below, used by fork() in case of fail.
+ */
+void perf_event_free_task(struct task_struct *task)
+{
+        struct perf_event_context *ctx;
+        struct perf_event *event, *tmp;
+        int ctxn;
+
+        for_each_task_context_nr(ctxn) {
+                ctx = task->perf_event_ctxp[ctxn];
+                if (!ctx)
+                        continue;
+
+                mutex_lock(&ctx->mutex);
+again:
+                list_for_each_entry_safe(event, tmp, &ctx->pinned_groups,
+                                group_entry)
+                        perf_free_event(event, ctx);
+
+                list_for_each_entry_safe(event, tmp, &ctx->flexible_groups,
+                                group_entry)
+                        perf_free_event(event, ctx);
+
+                if (!list_empty(&ctx->pinned_groups) ||
+                                !list_empty(&ctx->flexible_groups))
+                        goto again;
+
+                mutex_unlock(&ctx->mutex);
+
+                put_ctx(ctx);
+        }
+}
+
+void perf_event_delayed_put(struct task_struct *task)
+{
+        int ctxn;
+
+        for_each_task_context_nr(ctxn)
+                WARN_ON_ONCE(task->perf_event_ctxp[ctxn]);
+}
+
+/*
+ * inherit a event from parent task to child task:
+ */
+static struct perf_event *
+inherit_event(struct perf_event *parent_event,
+              struct task_struct *parent,
+              struct perf_event_context *parent_ctx,
+              struct task_struct *child,
+              struct perf_event *group_leader,
+              struct perf_event_context *child_ctx)
+{
+        struct perf_event *child_event;
+        unsigned long flags;
+
+        /*
+         * Instead of creating recursive hierarchies of events,
+         * we link inherited events back to the original parent,
+         * which has a filp for sure, which we use as the reference
+         * count:
+         */
+        if (parent_event->parent)
+                parent_event = parent_event->parent;
+
+        child_event = perf_event_alloc(&parent_event->attr,
+                                           parent_event->cpu,
+                                           child,
+                                           group_leader, parent_event,
+                                           NULL);
+        if (IS_ERR(child_event))
+                return child_event;
+        get_ctx(child_ctx);
+
+        /*
+         * Make the child state follow the state of the parent event,
+         * not its attr.disabled bit.  We hold the parent's mutex,
+         * so we won't race with perf_event_{en, dis}able_family.
+         */
+        if (parent_event->state >= PERF_EVENT_STATE_INACTIVE)
+                child_event->state = PERF_EVENT_STATE_INACTIVE;
+        else
+                child_event->state = PERF_EVENT_STATE_OFF;
+
+        if (parent_event->attr.freq) {
+                u64 sample_period = parent_event->hw.sample_period;
+                struct hw_perf_event *hwc = &child_event->hw;
+
+                hwc->sample_period = sample_period;
+                hwc->last_period   = sample_period;
+
+                local64_set(&hwc->period_left, sample_period);
+        }
+
+        child_event->ctx = child_ctx;
+        child_event->overflow_handler = parent_event->overflow_handler;
+
+        /*
+         * Precalculate sample_data sizes
+         */
+        perf_event__header_size(child_event);
+        perf_event__id_header_size(child_event);
+
+        /*
+         * Link it up in the child's context:
+         */
+        raw_spin_lock_irqsave(&child_ctx->lock, flags);
+        add_event_to_ctx(child_event, child_ctx);
+        raw_spin_unlock_irqrestore(&child_ctx->lock, flags);
+
+        /*
+         * Get a reference to the parent filp - we will fput it
+         * when the child event exits. This is safe to do because
+         * we are in the parent and we know that the filp still
+         * exists and has a nonzero count:
+         */
+        atomic_long_inc(&parent_event->filp->f_count);
+
+        /*
+         * Link this into the parent event's child list
+         */
+        WARN_ON_ONCE(parent_event->ctx->parent_ctx);
+        mutex_lock(&parent_event->child_mutex);
+        list_add_tail(&child_event->child_list, &parent_event->child_list);
+        mutex_unlock(&parent_event->child_mutex);
+
+        return child_event;
+}
+
+static int inherit_group(struct perf_event *parent_event,
+              struct task_struct *parent,
+              struct perf_event_context *parent_ctx,
+              struct task_struct *child,
+              struct perf_event_context *child_ctx)
+{
+        struct perf_event *leader;
+        struct perf_event *sub;
+        struct perf_event *child_ctr;
+
+        leader = inherit_event(parent_event, parent, parent_ctx,
+                                 child, NULL, child_ctx);
+        if (IS_ERR(leader))
+                return PTR_ERR(leader);
+        list_for_each_entry(sub, &parent_event->sibling_list, group_entry) {
+                child_ctr = inherit_event(sub, parent, parent_ctx,
+                                            child, leader, child_ctx);
+                if (IS_ERR(child_ctr))
+                        return PTR_ERR(child_ctr);
+        }
+        return 0;
+}
+
+static int
+inherit_task_group(struct perf_event *event, struct task_struct *parent,
+                   struct perf_event_context *parent_ctx,
+                   struct task_struct *child, int ctxn,
+                   int *inherited_all)
+{
+        int ret;
+        struct perf_event_context *child_ctx;
+
+        if (!event->attr.inherit) {
+                *inherited_all = 0;
+                return 0;
+        }
+
+        child_ctx = child->perf_event_ctxp[ctxn];
+        if (!child_ctx) {
+                /*
+                 * This is executed from the parent task context, so
+                 * inherit events that have been marked for cloning.
+                 * First allocate and initialize a context for the
+                 * child.
+                 */
+
+                child_ctx = alloc_perf_context(event->pmu, child);
+                if (!child_ctx)
+                        return -ENOMEM;
+
+                child->perf_event_ctxp[ctxn] = child_ctx;
+        }
+
+        ret = inherit_group(event, parent, parent_ctx,
+                            child, child_ctx);
+
+        if (ret)
+                *inherited_all = 0;
+
+        return ret;
+}
+
+/*
+ * Initialize the perf_event context in task_struct
+ */
+int perf_event_init_context(struct task_struct *child, int ctxn)
+{
+        struct perf_event_context *child_ctx, *parent_ctx;
+        struct perf_event_context *cloned_ctx;
+        struct perf_event *event;
+        struct task_struct *parent = current;
+        int inherited_all = 1;
+        unsigned long flags;
+        int ret = 0;
+
+        if (likely(!parent->perf_event_ctxp[ctxn]))
+                return 0;
+
+        /*
+         * If the parent's context is a clone, pin it so it won't get
+         * swapped under us.
+         */
+        parent_ctx = perf_pin_task_context(parent, ctxn);
+
+        /*
+         * No need to check if parent_ctx != NULL here; since we saw
+         * it non-NULL earlier, the only reason for it to become NULL
+         * is if we exit, and since we're currently in the middle of
+         * a fork we can't be exiting at the same time.
+         */
+
+        /*
+         * Lock the parent list. No need to lock the child - not PID
+         * hashed yet and not running, so nobody can access it.
+         */
+        mutex_lock(&parent_ctx->mutex);
+
+        /*
+         * We dont have to disable NMIs - we are only looking at
+         * the list, not manipulating it:
+         */
+        list_for_each_entry(event, &parent_ctx->pinned_groups, group_entry) {
+                ret = inherit_task_group(event, parent, parent_ctx,
+                                         child, ctxn, &inherited_all);
+                if (ret)
+                        break;
+        }
+
+        /*
+         * We can't hold ctx->lock when iterating the ->flexible_group list due
+         * to allocations, but we need to prevent rotation because
+         * rotate_ctx() will change the list from interrupt context.
+         */
+        raw_spin_lock_irqsave(&parent_ctx->lock, flags);
+        parent_ctx->rotate_disable = 1;
+        raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
+
+        list_for_each_entry(event, &parent_ctx->flexible_groups, group_entry) {
+                ret = inherit_task_group(event, parent, parent_ctx,
+                                         child, ctxn, &inherited_all);
+                if (ret)
+                        break;
+        }
+
+        raw_spin_lock_irqsave(&parent_ctx->lock, flags);
+        parent_ctx->rotate_disable = 0;
+
+        child_ctx = child->perf_event_ctxp[ctxn];
+
+        if (child_ctx && inherited_all) {
+                /*
+                 * Mark the child context as a clone of the parent
+                 * context, or of whatever the parent is a clone of.
+                 *
+                 * Note that if the parent is a clone, the holding of
+                 * parent_ctx->lock avoids it from being uncloned.
+                 */
+                cloned_ctx = parent_ctx->parent_ctx;
+                if (cloned_ctx) {
+                        child_ctx->parent_ctx = cloned_ctx;
+                        child_ctx->parent_gen = parent_ctx->parent_gen;
+                } else {
+                        child_ctx->parent_ctx = parent_ctx;
+                        child_ctx->parent_gen = parent_ctx->generation;
+                }
+                get_ctx(child_ctx->parent_ctx);
+        }
+
+        raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
+        mutex_unlock(&parent_ctx->mutex);
+
+        perf_unpin_context(parent_ctx);
+        put_ctx(parent_ctx);
+
+        return ret;
+}
+
+/*
+ * Initialize the perf_event context in task_struct
+ */
+int perf_event_init_task(struct task_struct *child)
+{
+        int ctxn, ret;
+
+        memset(child->perf_event_ctxp, 0, sizeof(child->perf_event_ctxp));
+        mutex_init(&child->perf_event_mutex);
+        INIT_LIST_HEAD(&child->perf_event_list);
+
+        for_each_task_context_nr(ctxn) {
+                ret = perf_event_init_context(child, ctxn);
+                if (ret)
+                        return ret;
+        }
+
+        return 0;
+}
+
+static void __init perf_event_init_all_cpus(void)
+{
+        struct swevent_htable *swhash;
+        int cpu;
+
+        for_each_possible_cpu(cpu) {
+                swhash = &per_cpu(swevent_htable, cpu);
+                mutex_init(&swhash->hlist_mutex);
+                INIT_LIST_HEAD(&per_cpu(rotation_list, cpu));
+        }
+}
+
+static void __cpuinit perf_event_init_cpu(int cpu)
+{
+        struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
+
+        mutex_lock(&swhash->hlist_mutex);
+        if (swhash->hlist_refcount > 0) {
+                struct swevent_hlist *hlist;
+
+                hlist = kzalloc_node(sizeof(*hlist), GFP_KERNEL, cpu_to_node(cpu));
+                WARN_ON(!hlist);
+                rcu_assign_pointer(swhash->swevent_hlist, hlist);
+        }
+        mutex_unlock(&swhash->hlist_mutex);
+}
+
+#if defined CONFIG_HOTPLUG_CPU || defined CONFIG_KEXEC
+static void perf_pmu_rotate_stop(struct pmu *pmu)
+{
+        struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
+
+        WARN_ON(!irqs_disabled());
+
+        list_del_init(&cpuctx->rotation_list);
+}
+
+static void __perf_event_exit_context(void *__info)
+{
+        struct perf_event_context *ctx = __info;
+        struct perf_event *event, *tmp;
+
+        perf_pmu_rotate_stop(ctx->pmu);
+
+        list_for_each_entry_safe(event, tmp, &ctx->pinned_groups, group_entry)
+                __perf_remove_from_context(event);
+        list_for_each_entry_safe(event, tmp, &ctx->flexible_groups, group_entry)
+                __perf_remove_from_context(event);
+}
+
+static void perf_event_exit_cpu_context(int cpu)
+{
+        struct perf_event_context *ctx;
+        struct pmu *pmu;
+        int idx;
+
+        idx = srcu_read_lock(&pmus_srcu);
+        list_for_each_entry_rcu(pmu, &pmus, entry) {
+                ctx = &per_cpu_ptr(pmu->pmu_cpu_context, cpu)->ctx;
+
+                mutex_lock(&ctx->mutex);
+                smp_call_function_single(cpu, __perf_event_exit_context, ctx, 1);
+                mutex_unlock(&ctx->mutex);
+        }
+        srcu_read_unlock(&pmus_srcu, idx);
+}
+
+static void perf_event_exit_cpu(int cpu)
+{
+        struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
+
+        mutex_lock(&swhash->hlist_mutex);
+        swevent_hlist_release(swhash);
+        mutex_unlock(&swhash->hlist_mutex);
+
+        perf_event_exit_cpu_context(cpu);
+}
+#else
+static inline void perf_event_exit_cpu(int cpu) { }
+#endif
+
+static int
+perf_reboot(struct notifier_block *notifier, unsigned long val, void *v)
+{
+        int cpu;
+
+        for_each_online_cpu(cpu)
+                perf_event_exit_cpu(cpu);
+
+        return NOTIFY_OK;
+}
+
+/*
+ * Run the perf reboot notifier at the very last possible moment so that
+ * the generic watchdog code runs as long as possible.
+ */
+static struct notifier_block perf_reboot_notifier = {
+        .notifier_call = perf_reboot,
+        .priority = INT_MIN,
+};
+
+static int __cpuinit
+perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
+{
+        unsigned int cpu = (long)hcpu;
+
+        switch (action & ~CPU_TASKS_FROZEN) {
+
+        case CPU_UP_PREPARE:
+        case CPU_DOWN_FAILED:
+                perf_event_init_cpu(cpu);
+                break;
+
+        case CPU_UP_CANCELED:
+        case CPU_DOWN_PREPARE:
+                perf_event_exit_cpu(cpu);
+                break;
+
+        default:
+                break;
+        }
+
+        return NOTIFY_OK;
+}
+
+void __init perf_event_init(void)
+{
+        int ret;
+
+        idr_init(&pmu_idr);
+
+        perf_event_init_all_cpus();
+        init_srcu_struct(&pmus_srcu);
+        perf_pmu_register(&perf_swevent, "software", PERF_TYPE_SOFTWARE);
+        perf_pmu_register(&perf_cpu_clock, NULL, -1);
+        perf_pmu_register(&perf_task_clock, NULL, -1);
+        perf_tp_register();
+        perf_cpu_notifier(perf_cpu_notify);
+        register_reboot_notifier(&perf_reboot_notifier);
+
+        ret = init_hw_breakpoint();
+        WARN(ret, "hw_breakpoint initialization failed with: %d", ret);
+}
+
+static int __init perf_event_sysfs_init(void)
+{
+        struct pmu *pmu;
+        int ret;
+
+        mutex_lock(&pmus_lock);
+
+        ret = bus_register(&pmu_bus);
+        if (ret)
+                goto unlock;
+
+        list_for_each_entry(pmu, &pmus, entry) {
+                if (!pmu->name || pmu->type < 0)
+                        continue;
+
+                ret = pmu_dev_alloc(pmu);
+                WARN(ret, "Failed to register pmu: %s, reason %d\n", pmu->name, ret);
+        }
+        pmu_bus_running = 1;
+        ret = 0;
+
+unlock:
+        mutex_unlock(&pmus_lock);
+
+        return ret;
+}
+device_initcall(perf_event_sysfs_init);
+
+#ifdef CONFIG_CGROUP_PERF
+static struct cgroup_subsys_state *perf_cgroup_create(
+        struct cgroup_subsys *ss, struct cgroup *cont)
+{
+        struct perf_cgroup *jc;
+
+        jc = kzalloc(sizeof(*jc), GFP_KERNEL);
+        if (!jc)
+                return ERR_PTR(-ENOMEM);
+
+        jc->info = alloc_percpu(struct perf_cgroup_info);
+        if (!jc->info) {
+                kfree(jc);
+                return ERR_PTR(-ENOMEM);
+        }
+
+        return &jc->css;
+}
+
+static void perf_cgroup_destroy(struct cgroup_subsys *ss,
+                                struct cgroup *cont)
+{
+        struct perf_cgroup *jc;
+        jc = container_of(cgroup_subsys_state(cont, perf_subsys_id),
+                          struct perf_cgroup, css);
+        free_percpu(jc->info);
+        kfree(jc);
+}
+
+static int __perf_cgroup_move(void *info)
+{
+        struct task_struct *task = info;
+        perf_cgroup_switch(task, PERF_CGROUP_SWOUT | PERF_CGROUP_SWIN);
+        return 0;
+}
+
+static void perf_cgroup_move(struct task_struct *task)
+{
+        task_function_call(task, __perf_cgroup_move, task);
+}
+
+static void perf_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
+                struct cgroup *old_cgrp, struct task_struct *task,
+                bool threadgroup)
+{
+        perf_cgroup_move(task);
+        if (threadgroup) {
+                struct task_struct *c;
+                rcu_read_lock();
+                list_for_each_entry_rcu(c, &task->thread_group, thread_group) {
+                        perf_cgroup_move(c);
+                }
+                rcu_read_unlock();
+        }
+}
+
+static void perf_cgroup_exit(struct cgroup_subsys *ss, struct cgroup *cgrp,
+                struct cgroup *old_cgrp, struct task_struct *task)
+{
+        /*
+         * cgroup_exit() is called in the copy_process() failure path.
+         * Ignore this case since the task hasn't ran yet, this avoids
+         * trying to poke a half freed task state from generic code.
+         */
+        if (!(task->flags & PF_EXITING))
+                return;
+
+        perf_cgroup_move(task);
+}
+
+struct cgroup_subsys perf_subsys = {
+        .name = "perf_event",
+        .subsys_id = perf_subsys_id,
+        .create = perf_cgroup_create,
+        .destroy = perf_cgroup_destroy,
+        .exit = perf_cgroup_exit,
+        .attach = perf_cgroup_attach,
+};
+#endif /* CONFIG_CGROUP_PERF */